PRACTICAL  SHIP  PRODUCTION 


5M?  Qraw-MlBook  &  1m 

PUBLISHERS     OF     BOOKS      F  O  R-^ 

Coal  Age  ^  Electric  Railway  Journal 
Electrical  World  v  Engineering  News-Record 
American  Machinist  v  The  Contractor 
Engineering 8 Mining  Journal  ^  Power 
Metallurgical  6  Chemical  Engineering 
Electrical  Merchandising 


PRACTICAL 
SHIP  PRODUCTION 


BY 

A.  W.  CARMICHAEL, 

LIEUTENANT   COMMANDER,    CONSTRUCTION   CORPS,   U.   8.    NAVY. 
MEMBER  SOCIETY  OP  NAVAL   ARCHITECTS  AND  MARINE  ENGINEERS. 


FIRST  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 

239  WEST  39TH  STREET.     NEW  YORK 


LONDON:  HILL  PUBLISHING  CO.,  LTD. 

6  &  8  BOUVERIE  ST.,  E.  C, 

1919 


COPYRIGHT,    1919,   BY  THE 

MCGRAW-HILL  BOOK  COMPANY,  INC. 


THE  MAPLE  PRESS  YORK  PA 


PREFACE 

The  purpose  of  this  book  is  to  present  in  convenient 
form  the  most  important  general  principles  of  ship  design, 
with  which  every  naval  architect  should  be  familiar,  and 
to  describe  the  various  processes  in  connection  with  the 
building  of  ships.  Its  nature  is  intended  to  be  practical 
rather  than  theoretical,  it  being  assumed  that  the  principal 
problem  with  which  the  reader  is  concerned  is  the  quick 
production  of  seagoing  vessels  from  plans  already  in  exist- 
ence rather  than  the  preparation  of  new  plans. 

The  recent  unprecedented  increase  in  shipbuilding  in  the 
United  States  has  resulted  in  a  corresponding  demand  for 
workmen,  draftsmen,  and  naval  architects.  It  has  there- 
fore become  necessary  for  many  engineers  and  technical 
men,  who  have  never  before  been  confronted  with  ship- 
building problems,  to  transfer  their  activities  from  the  fields 
of  the  various  other  engineering  professions  to  those  of  the 
marine  engineer  and  naval  architect.  These  men  are  fa- 
miliar with  mechanical  processes  and  have  the  necessary 
groundwork  in  theoretical  and  applied  mathematics  to 
fit  them  for  duties  in  connection  with  the  production  of 
ships,  but  lack  familiarity  with  those  matters  that  are 
peculiar  to  shipbuilding.  It  is  hoped  that  this  book  may 
aid  in  furnishing,  in  compact  form,  some  of  the  more  essen- 
tial parts  of  this  information.  It  should  also  be  of  value 
to  workmen  in  shipyards  who  have  only  such  knowledge 
of  the  shipbuilding  industry  as  they  have  gained  from 
practical  experience,  and  who  desire  to  fit  themselves  for 
higher  positions. 

It  is  manifestly  impossible  to  include  in  a  single  volume 
even  a  most  cursory  treatment  of  all  the  subjects  that  are 
involved  in  the  profession  of  naval  architecture,  Since, 


vi  PREFACE 

however,  matters  of  construction  are  to  be  considered 
more  fully  than  matters  of  design,  it  has  been  possible  to 
include  enough  matter  to  give  a  fairly  complete  general 
description  of  the  various  processes  in  the  production  of  a 
modern  steel  vessel.  A  certain  amount  of  space  has  been 
devoted  to  matters  of  a  theoretical  nature,  but  only  in  so  far 
as  it  has  been  believed  that  these  would  be  necessary  for  a 
proper  understanding  of  the  methods  of  construction. 

Certain  diagrams,  sketches  and  illustrations  have  been 
inserted  where  they  were  considered  necessary  for  a  proper 
understanding  of  the  subject  under  discussion.  Some  of 
the  sketches  are  not  accurately  proportioned,  having  been 
roughly  drawn  merely  for  the  purpose  of  showing  the 
principles  involved.  They  should  in  no  sense  be  consid- 
ered as  working  drawings. 

The  subject  matter  presented  is  not  new,  but  has  been 
gleaned  from  many  different  sources.  This  book  is  in  the 
nature  of  an  introduction  to  a  subject  upon  which  many 
books  have  been  written  and  of  which  a  complete  knowledge 
can  be  gained  only  by  reference  to  these  books,  and  by  ex- 
tended experience. 


CONTENTS 


PAGE 

PREFACE    v 

CHAPTER  I 

REQUIREMENTS  OF  SHIPS 

Introductory 1 

Buoyancy . 3 

Stability 5 

Propulsion 11 

Steering ' 20 

Strength 22 

Endurance .  28 

Utility 29 

CHAPTER  II 
GENERAL  DESCRIPTION  OF  SHIPS 

Form 31 

General  arrangement 41 

Types 50 

Tonnage 61 

Materials  used  in  construction 63 

CHAPTER  III 
STRUCTURAL  MEMBERS  OF  SHIPS 

Transverse  and  longitudinal  framing 77 

Stem,  stern  post,  rudder,  etc 91 

Shell  plating  and. inner  bottom 106 

Decks 114 

Bulkheads 121 

Miscellaneous 124 

CHAPTER  IV 
DESIGN  OF  SHIPS 

Conditions  to  be  fulfilled 130 

Choice  of  principal  elements 132 

Construction  of  lines  and  distribution  of  weights 133 

Principal  plans 134 

Final  calculations 136 

Detail  plans  and  specifications 146 

vii 


viii  CONTENTS 

CHAPTER  V 
SHIPYARDS 

PAGE 

Site  for  shipyard 147 

Building  slip  and  launching  ways     .    .  • 156 

Yard  layout,  shops,  storehouses,  etc 157 

Shipyard  machine  tools,  etc 163 

Personnel  of  a  shipyard 169 

Management 178 

CHAPTER  VI 
PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION 

Ordering  material 180 

Molds,  templates,  patterns,  etc ^  .    .    .    .    182 

Fabrication  of  material .    185 

CHAPTER  VII 
THE  BUILDING  OF  SHIPS 

Erection 195 

Bolting-up,  drilling  and  reaming  . 204 

Riveting 209 

Chipping,  calking  and  testing 219 

Protection  against  corrosion 224 

Welding 227 

Launching 231 

Fitting  out 237 

INDEX    .  .   243 


LIST  OF  ILLUSTRATIONS 


Fio.  No.  PAGE 

1.  Rectangular  floating  log 1 

2.  Forces  acting  on  floating  log 3 

3.  Centre  of  gravity  and  centre  of  buoyancy 5 

4.  Change  in  position  of  G  caused  by  load  on  top  of  log 6 

5.  Transverse  metacentre 6 

6.  Pendulum ...... 8 

7.  Variation  of  righting  arm 9 

8.  Log  hollowed  out  to  form  a  vessel 11 

9.  Streamlines. 12 

10.  Developments  of  ship  forms 13 

11.  "Similar"  ships 16 

12.  Rudder 20 

13.  Solid  and  built-up  hulls 23 

14.  Sagging  and  hogging 25 

15.  Curves  for  strength  calculation 26 

16.  "Lines"  of  a  ship -. 33 

17.  Parts  of  a  ship 38 

18.  Inboard  profile  of  cargo  steamer 43 

19.  Types  of  ships 59 

20.  Shipbuilding  shapes 65 

21.  Rivets 67 

22.  Types  of  keels 77 

23.  Simple  transverse  framing 80 

24.  Transverse  framing 81 

25.  Frame,  reverse  frame,  and  floor  plate 82 

26.  Intercostal  side  keelson 84 

27.  Side  stringer 85 

28.  Cross  section  of  a  ship  showing  longitudinal  framing 86 

29.  Diagrammatic  view  of  cellular  double  bottom  framing 86 

30.  Cross  section  of  double  bottom 87 

31.  Cross  section  of  cellular  double  bottom  with  intercostal  longitu- 

dinals      87 

32.  Longitudinal  section  of  cellular  double  bottom  showing  intercostal 

longitudinal 88 

33.  Bracket  floor 89 

34.  Watertight  floor,  cut  by  continuous  longitudinals 89 

35.  Stern  post  and  stem 92 

36.  Cross  section  of  lower  portion  of  cast  stem 93 

37.  Solid  cast  rudder 95 

38.  Single  plate  built  up  rudder 97 


x  LIST  OF  ILLUSTRATIONS 

FIG.  No.  PAGE 

39.  Cast  frame  of  side  plate  rudder 98 

40.  Pintle 99 

41.  Rudder  carrier,  etc 100 

42.  Bossing  and  stern  framing 101 

43.  Bossing  of  a  twin  screw  vessel 103 

44.  Propeller  struts 104 

45.  Stern  tube 105 

46.  Arrangement  of  plates  in  shell  plating 108 

47.  Systems  of  shell  plating 109 

48.  Butt  lap  with  tapered  liner  (seen  from  outside) 110 

49.  Butt  lap — one  plate  tapered  and  chambered  (seen  from  inside)  110 

50.  Stealer 112 

51.  Bulkhead  liner 113 

52.  Connections  of  deck  beams  to  frames 114 

53.  Deck  beams  and  carlings 115 

54.  Connections  at  sides  of  watertight  decks 116 

55.  Butt  of  deck  planking  over  steel  deck 117 

56.  Stanchion 119 

57.  Deck  girders 120 

58.  Covers  for  openings  in  watertight  decks 121 

59.  Bulkhead 123 

60.  Portion  of  engine  foundation 125 

61.  Boiler  saddles 126 

62.  Hawse  pipe 127 

63.  Bitts  and  chock .128 

64.  Rail  bulwarks,  fenders,  docking  keel,  bilge  keels 129 

65.  Value  of  BM 137 

66.  Atwood's  formula 139 

67.  Methods  of  integration 144 

68.  Making  a  shipyard 149 

69.  Building  slips 151 

70.  Keel  blocks  and  piling 152 

71.  Ship  on  launching  ways -  153 

72.  Launching 154 

73.  Shipyard  of  the  Submarine  Boat  Corporation 160 

74.  Operation  of  shipyard  machine  tools 164 

75.  Fabricated  parts 167 

76.  Shipfitting  work 174 

77.  Template  and  mold 184 

78.  Portion  of  bending  slab,  showing  frame  bending 189 

79.  Frame  beveling 190 

80.  Flat  and  centre  vertical  keel  plates  in  place  on  blocks 196 

81.  Drifting 197 

82.  Erecting  double  bottom  framing 198 

83.  Portion  of  double  bottom  framing  completely  erected 198 

84.  Ship  in  early  stage  of  construction 199 

85.  View  from  stern,  showing  frames,  deck  beams,  and  shaft  tunnel .    .  201 

86.  Cross  section  of  building  slip 202 


LIST  OF  ILLUSTRATIONS  xi 

FIG.  No.  PAGE 

87.  Wooden  ship  under  construction 203 

88.  Reaming 206 

89.  Effect  of  unfair  rivet  holes  and  improper  reaming 207 

90.  Method  of  using  pneumatic  drilling  machine 208 

91.  Driving  a  rivet 210 

92.  Improperly  driven  rivets 211 

93.  Safe  and  unsafe  loading  of  ropes 212 

94.  Safe  and  unsafe  loading  of  riveted  joints .    .    .  213 

95.  Cutting  out  rivets 215 

96.  Tap  rivets 217 

97.  Calking 220 

98.  Red  lead  putty  gun 223 

99.  Electric  quasi-arc  welding 230 

100.  Forces  acting  on  ships  during  launching 233 

101.  Inclining  experiment 239 


PRACTICAL 
SHIP  PRODUCTION 


CHAPTER  I 
REQUIREMENTS  OF  SHIPS 

INTRODUCTORY 

A  ship  may  be  defined  as  a  large  seagoing  vessel.  In 
other  words,  it  is  a  structure  that  will  float  and  is  capable 
of  making  ocean  voyages.  Its  purpose  is  to  furnish  a 
means  for  over-water  transportation.  It  may  be  con- 
sidered as  an  enlarged  boat.  It  is  convenient,  however, 


SIDE  ELEVATION 


END  ELEVATION 


W. 

De; 

i 

Freeboard 
3th                   Water  Line                 ^ 

L.           W. 

Water  Line 

i 

D^ft 

| 

1 

PLAN 

Be 

lm              Longitudinal  Centre  Line 

FIG.  1. — Rectangular  floating  log. 

at  the  start  to  consider  it  as  a  large  floating  log,  as  shown 
in  the  three  views  of  Fig.  1. 

Referring  to  this  figure,  the  following  should  be  noted: 
the  three  principal  dimensions  are  length,  beam,  and  depth. 

The  length  is  the  greatest  dimension  and  is  measured 
horizontally. 

The  beam  is  the  breadth  and  is  measured  horizontally 


2  PRACTICAL  SHIP  PRODUCTION 

. 
at  right  angles  to  the  length,  or  as  it  is  usually  expressed, 

athwartships. 

The  depth  is  measured  vertically  or  at  right  angles  to 
the  surface  of  the  water. 

The  form  is  shown  by  the  three  views  in  the  figure: 
side  elevation,  end  elevation,  and  plan.  (These  plans  are 
usually  called  by  other  names  in  the  case  of  a  ship,  as  will 
be  seen  later.) 

As  the  plane  of  the  surface  of  the  water  is  horizontal, 
the  intersections  of  this  plane  with  the  log  appear  in  the 
side  and  end  elevations  as  straight  horizontal  lines.  Each 
of  these  lines  is  called  the  water  line,  and  each  is  usually 
marked  by  a  UW"  at  one  end  and  "L"  at  the  other. 

The  intersections  of  a  vertical  longitudinal  plane  through 
the  longitudinal  axis  of  the  log  with  the  log's  form  appear 
as  straight  lines,  the  one  in  the  end  elevation  being  vertical 
and  the  one  in  the  plan  being  horizontal.  They  are  usually 
marked  "  k"  as  shown  in  the  figure,  and  are  called  centre 
lines.  The  draft  is  the  vertical  distance  to  which  the  log 
is  immersed.  The  freeboard  is  the  vertical  distance  that 
the  log  projects  above  the  surface  of  the  water. 

It  is  assumed  that  the  log  has  a  uniform  rectangular 
section  and  that  it  is  homogeneous  and  lighter  than  water. 
It  will  also  be  noted  that  it  floats  with  its  wider  side  hori- 
zontal. The  reasons  for  this  will  be  given  later. 

Such  a  log  represents  the  simplest  form  of  floating  body 
from  which  has  been  gradually  developed  the  modern 
ship,  and  in  the  following  pages  the  various  steps  in  the 
evolution  of  such  a  ship  from  a  simple  floating  body  will 
be  traced  and  the  various  requirements  of  all  ships  will 
be  discussed.  These  requirements  are  as  follows: 

Buoyancy. 

Stability. 

Propulsion. 

Steering. 

Strength. 

Endurance. 

Utility. 


REQUIREMENTS  OF  SHIPS  3 

1.  BUOYANCY 

Consider  a  log  floating  in  equilibrium  in  perfectly  still 
water,  as  shown  in  Fig.  1.  Assume  that  the  specific  grav- 
ity of  the  log  with  respect  to  the  water  in  which  it  floats 
is  0.5.  A  cross  section  of  the  log  is  shown  in  Fig.  2.  When 
it  is  floating  thus  at  rest  and  in  equilibrium,  the  forces 
on  the  log  will  be  balanced  as  follows: 

First. — The  forces  of  the  water  on  the  two  ends  will  balance 
each  other. 

Second. — The  forces  of  the  water  on  the  two  sides  will 
balance  each  other. 


Weight  of  Log 


Force  of  Buoyancy 
FIG.  2. — Forces  acting  on  floating  log. 

Third. — The  upward  pressure  of  the  water  uniformly  dis- 
tributed over  the  bottom  of  the  log  will  be  balanced  by 
the  uniformly  distributed  weight  of  the  log  acting  vertically 
downward  as  shown  in  the  figure. 

It  is  therefore  clear  that  the  upward  force  of  the  water 
pressure — which  is  called  the  buoyancy — is  exactly  equal 
to  the  weight  of  the  log.  But  if  the  space  occupied  by  the 
immersed  portion  of  the  log  be  replaced  by  water,  the  con- 
dition of  equilibrium  remains  unchanged,  and  therefore 
the  upward  force  of  the  pressure  of  the  water  acting  on 
the  bottom  of  the  log  is  exactly  equal  to  the  weight  of  the 
water  displaced  by  the  log,  which  is,  in  turn,  equal  to  the 
weight  of  the  log  itself. 


4  PRACTICAL  SHIP  PRODUCTION 

This  is  known  as  the  "Law  of  Floating  Bodies/7  and 
the  proof  given  above  for  the  case  of  a  floating  body  of 
simple  rectangular  form  may  be  extended  to  that  of  a 
body  of  any  form  by  the  method  of  resolution  of  forces. 
This  law  may  be  briefly  stated  for  all  ships  as  follows: 

The  weight  of  any  ship  floating  in  water,  including  all 
that  she  carries,  must  equal  the  weight  of  the  water  that  she 
displaces. 

When  the  draft  at  which  any  ship  floats  is  known,  it  is 
possible  to  calculate  the  volume  of  the  ship  that  is  below 
the  surface  of  the  water.  The  weight  of  the  ship  plus  all 
that  she  carries  can  thus  be  obtained,  provided  the  density 
of  the  water  in  which  she  floats  is  known. 

In  the  case  of  the  log  referred  to  above  (which  has  a 
density  of  0.5),  it  is  clear  that  the  log  will  be  half  above  and 
half  below  the  water,  since  the  weight  of  an  amount  of 
water  of  one-half  of  the  volume  of  the  log  is  equal  to  the 
total  weight  of  the  log.  If  the  density  of  the  log  be  in- 
creased, the  amount  of  the  log  immersed  increases,  and  if 
the  density  becomes  greater  than  1.0  the  log  will  sink. 
Similarly,  if  the  weight  of  a  ship  with  everything  that  she 
carries  becomes  greater  than  the  weight  of  the  volume  of 
water  that  she  is  capable  of  displacing,  she  will  sink. 

The  total  weight  of  the  log  may  be  considered  as  acting 
vertically  downward  through  its  centre  of  gravity,  and  the 
equal  force  of  buoyancy  as  acting  vertically  upward  through 
the  centre  of  gravity  of  the  displaced  water,  or  the  centre 
of  figure  of  the  under  water  portion  of  the  log.  This  point 
is  called  the  centre  of  buoyancy.  The  centre  of  gravity 
of  a  floating  object  is  usually  called  G,  and  the  centre  of 
buoyancy,  B.  In  the  case  of  the  log,  G  is  at  the  centre  of 
the  cross  section  and  B  is  halfway  between  G  and  the 
bottom  of  the  log.  (See  Fig.  3.) 

Since  the  force  of  buoyancy  acts  vertically  upward 
and  the  weight  of  the  log  acts  vertically  downward,  it  is 
clear  that  for  equilibrium  G  and  B  must  be  in  the  same  ver- 
tical line,  for,  were  this  not  the  case,  there  would  be  a 


REQUIREMENTS  OF  SHIPS  5 

couple  tending  to  produce  rotation,  and  equilibrium  would 
no  longer  exist. 

This  is  another  important  law  of  floating  bodies,  and  may 
be  briefly  stated:  The  centre  of  gravity  and  the  centre  of 
buoyancy  of  a  ship  floating  in  equilibrium  in  still  water 
must  be  in  the  same  vertical  line. 

For  the  two  principles  just  enunciated  to  be  strictly 
true,  it  is  necessary  that  the  water  be  entirely  displaced  by 
the  portion  of  the  floating  body  that  is  under  water.  The 
"skin"  of  a  ship  must  therefore  be  absolutely  water-tight. 
The  requirements  of  buoyancy  for  all  ships  and  other  craft 
may  then  be  summarized  as  follows:  'The  vessel  must 


FIG.  3. — Centre  of  gravity  and  centre  of  buoyancy. 

be  so  designed  and  constructed  that  it  will  float,  in  equilib- 
rium,  in  such  a  position  as  to  displace  by  its  hull  an  amount 
of  water  equal  to  its  own  weight. 

A  simple  rectangular  log  of  the  shape  shown  in  the  pre- 
ceding sketches  fulfils  this  requirement,  and  such  a  log, 
if  of  sufficient  size,  might  be  used  as  a  means  for  transport- 
ing merchandise  or  men  over  smooth  bodies  of  water.  It 
is  probable  that  the  first  crude  means  of  over-water  trans- 
portation were  logs.  There  are,  however,  certain  practical 
difficulties  in  the  way  of  this  means,  the  principal  of  which 
is  lack  of  stability — a  quality  which  will  be  next  discussed. 

2.  STABILITY 

Let  it  be  assumed  that  the  log  be  loaded  so  that  it  sinks  to 
a  position  as  shown  in  Fig.  4,  and  let  the  total  weight  of 
the  log  and  its  load  be  W.  The  centre  of  buoyancy  B  will  be 


6 


PRACTICAL  SHIP  PRODUCTION 


at  the  centre  of  figure  of  the  immersed  cross  section,  (Fig. 
4  being  assumed  to  be  a  transverse  section  through  the 
middle  of  the  log),  but  owing  to  the  added  weight  on 
the  top  of  the  log,  the  position  of  the  centre  of  gravity  of  the 


FIG.  4. — Change  in  position  of  G  caused  by  load  on  top  of  log. 

log  and  load  will  be  higher  than  that  of  the  log  only.  Any 
weight  placed  on  the  top  of  the  log  will  tend  to  make  it 
"top  heavy." 

Suppose  that  the  log  and  load  be  inclined  from  the  ver- 
tical position,  by  some  external  force,  to  the  position  shown 


FIG.  5. — Transverse  metacentre. 


in  Fig.  5.  The  centre  of  buoyancy,  which  is  the  centre  of 
figure  of  the  immersed  portion  of  the  log,  will  move  from 
B,  relative  to  the  log,  to  some  position,  such  as  Bf.  The 
centre  of  gravity,  G,  however,  remains  unchanged  relative 
to  the  log.  Since  the  weight  of  the  log  and  its  load  W  and 


REQUIREMENTS  OF  SHIPS  7 

the  force  of  buoyancy  must  still  be  equal,  there  will  be  set 
up  a  couple,  of  force  W,  and  arm  GZ,  GZ  being  the  distance 
between  the  vertical  lines  through  G  and  B'.  If  the  ver- 
tical through  Bf  intersects  the  line  BG  above  G,  this  couple 
will  tend  to  produce  rotation  in  the  direction  shown  by  the 
curved  arrow  and  to  right  the  log.  If  it  intersects. BG  below 
G  it  will  tend  to  produce  rotation  in  the  opposite  direction, 
and  to  capsize  the  log.  If  it  intersects  it  at  G,  there  will 
be  no  couple  and  no  tendency  to  rotation  in  either  direction. 

The  first  condition  (before  the  external  force  was  applied) 
is  called  one  of  stable  equilibrium;  the  second,  one  of  unstable 
equilibrium;  and  the  third,  one  of  neutral  equilibrium. 

The  point  M  at  which  the  vertical  through  B'  intersects 
the  line  BG,  is  called  the  transverse  metacentre,  or  often 
simply  the  metacentre.  The  distance  GZ  is  called  the  righting 
arm  and  it  will  be  noted  that  the  greater  the  length  GZ  the 
greater  will  be  the  couple  tending  to  right  the  log.  Also,  if 
e  be  the  angle  to  which  the  log  is  inclined  GZ  equals  GM 
sin  6,  so  that  for  any  given  inclination  the  greater  the  length 
of  the  righting  arm  the  greater  will  be  the  value  of  GM. 
The  position  of  M  remains  practically  constant  for  small 
angles  of  inclination  (up  to  say  10°)  and  the  length  GM  for 
such  angles  is  known  as  the  metacentric  height. 

The  higher  M  is  above  G,  the  greater  will  be  the  value  of 
GM ,  the  metacentric  height,  and  of  the  righting  arm,  and 
consequently  the  greater  will  be  the  tendency  of  the  log 
to  right  itself  when  slightly  inclined  from  the  upright 
position. 

It  is  apparent  from  the  above  that  the  amount  of  weight 
that  can  be  carried  on  top  of  the  log  without  unduly 
reducing  the  value  of  the  metacentric  height,  and  hence 
the  tendency  for  the  log  to  remain  upright,  is  very  limited. 
This  tendency  to  remain  upright  is  called  initial  stability. 
Since  all  weight  added  to  the  log  above  its  own  centre  of 
gravity  will  result  in  the  location  of  the  combined  centre 
of  gravity  moving  upward,  and  since  M  is  above  G,  to  start 
with,  the  addition  of  weight  on  top  of  the  log  will  reduce  the 
metacentric  height,  GM. 


8 


PRACTICAL  SHIP  PRODUCTION 


•  G 


The  metacentric  height  of  any  vessel  is  therefore  a  very 
important  characteristic,  since  it  is  a  measure  of  the 
vessel's  initial  stability,  or  safety  against  capsizing.  The 
vessel  may  be  considered  as  a  pendulum  of  which  M  is  the 
point  of  support  and  G  the  point  at  which  the  total  mass 
may  be  conceived  as  concentrated.  If  M  be  moved  down 
to  G  the  pendulum  will  pass  from  a  position  of  stable  to  one 
of  neutral  equilibrium.  The  instant  M  passes  below  G,  the 
.  equilibrium  becomes  unstable.  (See  Fig.  6.) 

The  metacentric  height  is,  however,  im- 
portant only  in  that  it  is  a  measure  of  the 
initial  righting  arm.  The  righting  arm  multi- 
plied by  the  total  weight  of  the  floating  body 
gives  the  value  of  the  moment  tending  to  pre- 
vent capsizing.  For  angles  of  inclination 
greater  than  about  10°  the  position  of  the 
metacentre  changes,  so  that  the  righting  arm 
itself  must  be  considered. 

Let  it  be  assumed  that  the  log  be  loaded  in 
such  a  way  that  its  total  weight,  including  the 
load,  be  W,  and  that  its  centre  of  gravity  be  as 
shown  in  Fig.  7  (1).  Now  let  it  be  supposed 
that  the  log  be  inclined  by  some  external 
horizontal  force  so  that  it  passes  successively 
through  the  five  positions  shown  in  Fig.  7  (1), 
(2),  (3),  (4),  and  (5).  It  will  be  noted  that 
when  the  log  is  upright  in  the  water  the  value 
of  the  righting  arm  GZ  is  zero,  since  the  forces 
of  the  weight  and  the  buoyancy  both  act  in  the 
same  vertical  line.  As  the  log  is  first  inclined,  the  length 
of  the  righting  arm  increases  at  a  comparatively  rapid 
rate,  as  shown  in  Fig.  7  (2).  This  is  due  to  the  fact  that 
the  centre  of  buoyancy  is  moving  to  the  right  of  the 
figure  on  account  of  the  increased  immersed  volume  of 
the  log  on  that  side,  the  centre  of  buoyancy  being  the 
geometrical  centre  of  figure  of  that  immersed  volume.  It 
will  be  noted  that  after  the  right  hand  upper  edge  of  the 
log  is  immersed,  the  movement  of  B  toward  the  right  still 


t.    6. — Pen- 
dulum. 


REQUIREMENTS  OF  SHIPS 


9 


continues,  but  at  a  diminishing  rate,  because  of  the  water 
now  above  the  corner  which  causes  the  immersed  centre  of 
figure  to  slow  down  in  its  movement  to  the  right.  An  in- 
clination will  finally  be  reached  (as  shown  in  Fig.  7  (3))  at 
which  the  righting  arm  is  a  maximum,  and  its  rate  of  in- 
crease is  zero.  Any  further  inclination  will  produce  a  di- 
minution in  the  righting  arm  which  has  already  become 
smaller  when  the  position  shown  at  Fig.  7  (4)  has  been 
reached.  Finally,  at  some  such  inclination  as  that  shown 
in  Fig.  7  (5),  the  righting  arm  will  again  become  zero  and 
the  stability  will  vanish. 


(1)  Upright  Position 


(2)  Upper  Corner 
Immersed 


(3)  Maximum  Righting 
Arm 


(1)     Angle  of  Inclination 

CURVE  OF  RIGHTING  ARMS 
FIG.  7. — Variation  of  righting  arm. 

This  inclination  at  which  the  stability  vanishes  is  called 
the  angle  of  vanishing  stability  or  range  of  stability,  and  the 
inclination  at  which  the  righting  arm  is  a  maximum  is 
called  the  angle  of  maximum  stability.  A  curve  is  plotted  in 
Fig.  7  showing  how  the  righting  arm  increases  to  a  maxi- 
mum, diminishes,  and  finally  vanishes  as  the  inclination 
increases  from  that  shown  in  sketch  (1)  to  that  shown  in 
sketch  (5).  From  this  curve  it  will  be  noted  that  the 
maximum  righting  moment  occurs  when  the  log  is  inclined 
to  an  angle  of  about  35°  from  its  upright  position,  and  that 
if  the  log  be  inclined  to  an  angle  much  greater  than  50°  from 
the  upright  it  will  capsize. 


10  PRACTICAL  SHIP  PRODUCTION 

These  considerations  which  have  been  discussed  in 
connection  with  the  simple  rectangular  log,  apply  to  all 
floating  bodies,  but  in  the  case  of  ships  and  other  vessels  of 
irregular  form,  the  mathematical  calculations  involved 
in  obtaining  values  of  the  righting  arms  for  various  angles 
of  heel  become  much  more  involved.  It  should  also  be 
noted  that  as  well  as  being  inclined  transversely,  the  vessel 
may  be  at  the  same  time  inclined  longitudinally,  thus  mak- 
ing the  problem  still  more  difficult.  For  practical  purposes, 
however,  in  the  case  of  ships  it  is  usually  sufficient  to  con- 
sider transverse  inclinations  only,  since  the  length  of  ordinary 
ships  is  so  much  greater  than  their  beam  that  their  longi- 
tudinal stability  is  always  ample. 

The  elementary  principles  of  stability  enunciated  above 
having  been  carefully  considered  it  will  be  noted  that  the 
use  of  a  log  loaded  on  its  top  as  a  means  for  over-water 
transportation  is  very  limited.  If  the  weight  be  placed  on 
the  top,  the  centre  of  gravity  will  be  raised  and  the  initial 
stability  consequently  reduced.  Also,  the  angle  to  which 
the  loaded  log  may  be  safely  inclined  depends  further 
upon  the  proportions  of  the  log.  Referring  to  Fig.  7, 
it  will  be  noted  that  the  amount  of  the  log  above  water 
determines  the  point  (2)  at  which  the  rate  of  increase  of 
the  righting  arm  commences  to  diminish  and  thus  influences 
the  range  of  stability  (since  that  is  the  point  at  which  the 
upper  edge  of  the  log  becomes  immersed).  Furthermore, 
the  width  of  the  log  influences  the  maximum  righting  arm 
since  the  point  B3  will  be  farther  to  the  right,  and  the  length 
GZZ  (in  Fig.  7  (3))  greater  if  the  width  of  the  log  be  greater. 
Also,  the  higher  the  position  in  the  log  of  G,  which  is  the 
centre  of  gravity,  the  smaller  will  be  the  righting  arm. 

The  following  points  are  therefore  apparent  from  the 
standpoint  of  stability:  first,  the  width  of  the  log  should, 
as  a  general  rule,  be  greater  than  the  depth;  second,  the 
amount  of  the  log  above  the  water  should  not  be  too  small ; 
and  third,  the  centre  of  gravity  of  the  log  and  all  that  it 
carries  should  be  kept  as  low  as  possible. 

These  considerations  led  to  the  first  step  in  the  evolution 


REQUIREMENTS  OF  SHIPS 


11 


of  vessels  or  floating  objects  hollowed  out.  By  these  means 
it  becomes  possible  to  carry  the  same  load  with  the  position 
of  the  centre  of  gravity  much  lower,  thus  increasing  the 
stability  and  still  retaining  practically  the  same  freeboard. 
(See  Fig.  8.) 

A  hollowed-out  log  or  dug-out,  the  rude  canoe  of  pre- 
historic man,  was  the  first  boat.  As  the  need  for  larger 
craft  was  felt,  it  became  necessary  to  use  more  than  one 
piece  of  material,  and  canoes  were  then  fabricated  of  wood, 
skins,  bark,  and  other  materials.  But  the  object  to  be 
attained  was  still  the  same — to  secure  a  hollow  structure 
that  would  keep  out  the  water  and  permit  a  larger  weight 


FIG.  8. — Log  hollowed  out  to  form  a  vessel. 

to  be  carried  without  endangering  the  buoyancy  and  sta- 
bility. Consideration  may  now  pass  from  the  rectangular 
log  to  built-up,  box-shaped  vessels,  which  have  the  same 
external  form  and  possess  the  first  two  requirements  of  a 
ship,  buoyancy  and  stability.  Such  vessels  can  be  safely 
loaded  with  large  and  heavy  cargoes,  but  still  are  of  little 
practical  value  unless  they  can  be  moved  from  place  to 
place  by  water. 

3.  PROPULSION 

It  is  apparent  from  an  inspection  of  Fig.  1,  which  may 
now  be  considered  as  representing  a  large  water-tight 
floating  box,  that  the  water  would  offer  considerable 
resistance  in  case  it  were  attempted  to  move  such  a  vessel 


12 


PRACTICAL  SHIP  PRODUCTION 


from  place  to  place.  It  would,  of  course,  be  natural  to 
move  the  vessel  endwise  rather  than  sidewise,  but  even  so, 
the  square  ends  would  offer  a  great  resistance  to  the  water. 
Figure  9  shows  the  paths  of  the  particles  of  water  relative  to 
such  a  vessel  moving  in  the  direction  indicated  by  the  arrow. 
These  paths  of  the  water  particles  are  known  as  stream 
lines.  The  end  of  the  vessel  that  enters  the  water  is 
called  the  bow,  and  the  other  end,  the  stern.  Owing  to  the 
sudden  change  of  direction  of  the  stream  lines  at  the  bow 
and  stern,  considerable  energy  must  be  expended  in  driving 


Eddy 


Stern 


Bow 


Eddy 


Eddy 


FIG.  9. — Stream  lines. 


or  towing  such  a  vessel  through  the  water.  Part  of  this 
energy  is  expended  in  wave  making,  part  in  eddy  making,  and 
part  in  overcoming  the  friction  of  the  water  in  contact  with 
the  sides,  ends,  and  bottom  of  the  vessel. 

In  order  to  reduce  these  various  forms  of  resistance  as 
much  as  possible,  it  is  desirable  to  change  the  form  and 
reduce  the  length  of  the  stream  lines.  This  consideration 
naturally  leads  to  the  sharpening  of  the  bow  and  the 
tapering  of  the  stern  of  the  vessel,  as  shown  in  Fig.  10  (a), 
and  a  further  development  is  to  make  the  outline  a  smooth 
curve,  as  shown  in  Fig.  10  (6).  For  similar  reasons 
it  is  natural  to  round  off  the  lower  edges,  or,  as  they  are 
called,  the  bilges  of  the  vessel,  as  shown  in  Fig.  10  (c). 
These  changes,  and  other  similar  ones  made  from  time  to 


REQUIREMENTS  OF  SHIPS 


13 


time,  have  resulted  in  the  present  ship-shape  form  of 
most  vessels.  The  most  important  of  these  changes, 
however,  have  been  made  at  the  ends,  and  most  vessels 
still  retain  in  their  middle  portion  a  form  that  is  prac- 
tically box  shaped.  This  is  particularly  true  of  slow 
moving  vessels,  such  as  tramp  steamers,  oil  tankers,  barges, 
etc. 


Water  Line  pointed  at  ends 


(a) 


-Bilges  rounded  off- 


(0 
FIG.  10. — Developments  of  ship  forms. 

Having  given  the  vessel  a  ship-shape  form,  it  is  now 
possible  to  have  it  move  from  place  to  place  without  such 
an  uneconomical  expenditure  of  energy. 

Among  the  first  means  of  propulsion  of  boats  and  other 
small  craft  were  poles,  paddles,  and  oars,  and  finally,  sails. 
It  is  also  possible  to  tow  one  vessel  by  a  tow  line  from 
another,  or  from  the  banks  of  a  canal.  Since  the  intro- 
duction of  steam,  however,  and  with  the  increase  in 
size  of  vessels,  the  majority  of  all  but  the  smallest  have 
been  propelled  by  machinery — at  first  through  the  medium 


14  PRACTICAL  SHIP  PRODUCTION 

of  paddle  wheels,  and  finally,  by  the  more  efficient  means  of 
screw  propellers.  (Another  means  is  that  of  the  jet 
propeller,  by  which  a  stream  of  water  is  forced  outwards 
from  the  hull  so  as  to  drive  the  vessel  ahead,  but  this 
method  has  never  been  extensively  used). 

At  the  present  time  practically  all  self-propelled  vessels 
are  driven  through  the  water  by  means  of  screw  propellers 
mounted  on  shafts  at  their  sterns.  The  shafts  may  be 
rotated  by  means  of  gasoline,  kerosene,  oil,  or  other  internal 
combustion  motors,  by  steam  engines  of  the  reciprocating 
type,  by  steam  turbines  with  or  without  reduction  gearing, 
or  by  electric  motors. 

The  action  of  the  screw  propeller  may  be  compared  to 
that  of  a  screw  or  threaded  bolt.  Any  motion  of  rotation 
of  the  bolt  is  accompanied  by  a  corresponding  motion  of 
translation  along  its  axis.  The  surfaces  of  the  blades  of  a 
screw  propeller  are  simply  portions  of  the  surface  of  a 
helix  or  screw,  the  difference  in  the  action  of  the  propeller 
from  that  of  a  screw  in  a  solid  nut  being  largely  due  to  the 
slipping  of  the  propeller  in  the  surrounding  water. 

It  is  possible  to  determine  in  advance  what  will  be  the 
effect  of  a  certain  propeller  in  driving  a  given  vessel  through 
the  water,  provided  the  amount  of  power  that  will  be 
applied  to  it  be  known.  When  a  vessel  is  to  be  driven  by 
a  screw  propeller  (or  by  two  or  more  such  propellers) 
it  is  therefore  a  great  advantage  to  be  able  to  know  in 
advance  how  much  power  will  be  required  to  propel  the 
vessel  at  the  desired  speed.  This  is  one  of  the  most 
important  considerations  in  the  design  of  a  ship,  especially 
where  speed  is  an  important  requirement,  since  the  power 
required  will  determine  the  amount  of  weight  and  space 
that  must  be  devoted  to  engines,  boilers,  etc.  The  method 
in  common  use  for  determining  the  power  required  for  a 
given  ship  is  known  as  the  method  of  comparison. 

For  an  explanation  of  this  method,  a  few  simple  mechan- 
ical laws  must  be  considered.  Power  is  the  rate  at  which 
work  is  done,  and  work  is  measured  by  the  force  acting 
multiplied  by  the  distance  through  which  it  acts.  In  the 


REQUIREMENTS  OF  SHIPS  15 

case  of  a  ship  the  force  acting  must  be  a  force  equivalent 
to  the  resistance  to  motion  offered  by  the  water  through 
which  the  ship  is  driven,  the  distance  being  the  distance 
through  which  the  ship  moves. 

If  it  is  desired  to  design  an  engine  to  hoist  a  given 
weight  at  a  certain  specified  speed,  the  problem  is  a  simple 
one,  since  the  power  required  is  simply  the  product  of  the 
speed  times  the  weight  or  force  to  be  overcome.  In  the 
case  of  a  ship,  however,  the  problem  is  not  so  simple  since 
the  resistance  offered  to  the  ship's  motion  is  influenced  to 
a  considerable  extent  by  the  action  of  the  particles  of  water 
through  which  the  ship  passes. 

A  mathematical  calculation  of  the  resistance  of  a  ship, 
even  of  the  simplest  form  is  a  very  difficult  problem,  and 
with  the  practically  infinite  number  of  different  forms  that 
it  is  possible  to  give  to  a  ship,  the  problem  becomes  still 
further  involved.  It  has  therefore  been  found  more 
desirable  to  determine  the  power  required  to  drive  a  given 
ship  by  the  practical  method  of  comparison.  For  instance, 
if  one  ship  is  to  be  built  the  exact  duplicate,  in  all  respects, 
of  another  ship  that  has  already  been  built  and  put  into 
service,  then  the  power  of  the  engines  required  for  the  con- 
templated ship,  in  order  to  drive  her  at  the  same  speed  as 
the  completed  ship  under  exactly  similar  conditions,  should 
be  the  same.  This  is  the  simplest  case.  If  the  contem- 
plated ship  is  to  have  the  same  form  and  proportions  as 
the  completed  ship,  but  is  to  be  either  larger  or  smaller, 
it  is  natural  to  assume  that  there  must  be  some  law  by 
means  of  which  the  two  ships  can  be  compared  so  as  to  deter- 
mine in  advance  the  power  that  will  be  required  for  the 
contemplated  ship. 

Let  it  be  assumed  that  it  is  proposed  to  build  a  ship  of 
exactly  the  same  form  and  proportions  as  those  of  another 
ship  already  completed  and  data  regarding  the  performance 
of  which  is  available,  the  length  of  the  proposed  ship, 
however,  to  be  different  from  that  of  the  completed  ship. 
The  two  ships  are  shown  in  Fig.  11,  and  calling  them  ships 
"No.  1"  and  "No.  2,"  as  indicated,  let  it  be  assumed 


16  PRACTICAL  SHIP  PRODUCTION 

that  "  No.  2  "  is  n  times  as  long  as  "  No.  1."  Then  referring 
to  Fig.  11,  the  lengths,  beams,  and  depths  of  the  two  ships 
are  as  follows:  L,  nL,  B,  nB,  D,  nD,  respectively.  The 
area  of  the  rectangle  circumscribing  ship  "No.  1"  is 
B  X  L,  and  ship  "No.  2"  is  nB  X  nL  or  n*BL.  The 
volume  of  ship  "No.  I"  is  a  certain  proportion  of  L  X 
B  X  D,  and  the  volume  of  ship  "No.  2"  is  the  same 
proportion  of  nL  X  nB  X  nD,  or  n*LBD.  In  other 
words,  the  ratio  on  ships  "  Nos.  2"  and  "1 "  of  corresponding 
linear  measurements  is  n}  of  corresponding  surface 
measurements  is  n2,  and  of  corresponding  volumetric 
measurements  is  n3.  The  volume  of  water  displaced  by 
ship  "No.  2"  is  thus  n3  times  as  great  as  that  displaced 
by  "No.  1,"  and  consequently,  the  weight,  or,  as  it  is 


CD 

!<  D  >: 


SHIP  NO.  1. 


Ill 


SHIP  NO.  2.  ' 

FIQ.  11. — Similar  ships. 

usually  called,  the  displacement,  of  "No.  2"  is  n3  times  that 
of  "No.  1."  Displacement  of  "No.  1"  equals  W; 
displacement  of  "No.  2"  equals  n*W. 

The  displacement  being  a  weight,  is  also  a  force,  and 
therefore  should  be  expressed  in  the  same  units  as  the 
resistance,  which  is  also  a  force.  Consequently,  if  R 
be  the  resistance  of  ship  "No.  1,"  the  resistance  of  ship 
"No.  2"  should  be  n*R. 

Let  the  speed  of  ship  "No.  1"  be  Vi  and  that  of  ship 
"No.  2"  be  72.  Speed  is  the  distance  through  which 
the  vessel  moves  per  unit  of  time,  or  if  ti  is  the  length  of 
time  required  by  ship  "No,  1 "  to  travel  forward  a  distance 
equal  to  its  own  length,  and  tz  the  time  required  by  ship 
"No.  2"  to  travel  forward  a  distance  equal  to  its  own 
length,  then 


REQUIREMENTS  OF  SHIPS  17 

L^ 

Vi  _    ti_      h      1 

F2  ""  nL  ~  ti      n 
~h 

Let  the  accelerations  of  ships  "Nos.  1"  and  "2"  be, 
respectively,  <*  ly  and  cc  2.  Acceleration  is  by  definition, 
rate  of  increase  of  velocity; 


" 


Assuming  that  gravity  is  constant,  the  masses  of  ships 
Nos.  1"  and  "2"  are  proportionate  to  their  weights,  or 
MI  and  M2  are  their  respective  masses,  then 

Mi        W 


The  respective  resistances  being  forces,  may  be  expressed 
as  the  products  of  their  respective  masses  and  accelerations; 
consequently 

or 

|  =  Vn 

But  it  has  been  shown  that 


K2       ti^n 
Consequently 


or 


This  simple  equation  represents  a  fact  that  is  very  useful 

to  ship  designers.     It  may  be  expressed  in  words  as  follows : 

When  comparing  one  ship  with  another  simitar  ship,  for  the 


18  PRACTICAL  SHIP  PRODUCTION 

purpose  of  determining  the  resistance  at  any  given  speed, 
the  respective  speeds  of  the  two  ships  must  be  in  the  same 
ratio  as  the  square  root  of  the  ratio  of  the  linear  dimensions 
of  the  two  ships. 

When  speeds  are  so  taken  they  are  known  as  corresponding 
speeds.  By  similar  ships  are  meant  ships  having  the  same 
geometrical  form,  all  corresponding  dimensions  having  the 
same  ratio,  and  all  weights  being  similarly  distributed  and 
varying  as  the  third  power  of  the  linear  ratio. 

For  example,  if  ship  "No.  2"  is  to  be  four  times  as  long 
as  ship  "" No.  1,"  the  speed  to  be  used  for  ship  "No.  1" 
should  be  one-half  of  the  speed  to  be  used  for  ship  "No.  2" 
when  making  the  comparison. 

Since  power  is  measured  by  the  rate  at  which  work  is 
done,  and  since  work  is  measured  by  the  product  of  the 
force  overcoming  the  resistance  multiplied  by  the  distance 
through  which  this  force  acts,  the  power  required  for  the 
proposed  ship  may  be  determined  as  follows:  Let  PI  and 
P2  be  the  respective  powers  of  ships  "Nos.  1  and  2."  The 
forces  of  resistance  are,  respectively,  R  and  n*R.  The 
distances  through  which  these  forces  act  in  a  unit  of  time 
are  respectively  V\  and  F2,  and  since  power  is  work  done 
per  unit  of  time, 

Pi  _     flXFi        1  ~ .  JL       JL 
P2      n*R  X  V2      n*      \/n  "  nA 

P2  =  rPPi 

which  may  be  expressed  in  words: 

The  ratio  of  the  powers  at  corresponding  speeds  of  two 
similar  ships  is  equal  to  the  %  power  of  the  ratio  of  their 
linear  dimensions. 

This  lawls  very  useful  for  comparing  ships  that  are  similar. 
This  and  the  preceding  law  are  merely  extensions  of  the 
principle  of  mechanical  similitude,  the  application  of  which 
to  ships  was  first  demonstrated  by  Mr.  Wm.  Froude,  who 
was  one  of  England's  most  prominent  naval  architects. 
They  are  usually  combined  and  expressed  in  terms  of 


REQUIREMENTS  OF  SHIPS  19 

resistance  instead  of  power,  as  Fronde's  Law  of  Comparison, 
as  follows: 

//  two  ships  are  exactly  similar,  and  n  is  the  ratio  of  their 
corresponding  linear  dimensions,  then  if  they  be  run  at  speeds 
proportional  to  \/n,  the  ratio  of  the  corresponding  resistances 
will  be  nz. 

This  law  furnishes  a  means  for  comparing  one  ship  with 
another  similar  ship  provided  their  sizes  do  not  differ  to 
any  great  extent.  If,  however,  no  ship  has  ever  been  built 
that  has  the  same  form  as  the  ship  being  designed,  it  be- 
comes necessary  to  make  a  model  of  the  proposed  ship, 
the  resistance  of  which  model  can  be  readily  determined, 
by  experiment,  in  a  large  long  tank  called  a  model  tank,  by 
towing  the  model  and  measuring  its  resistance.  If  it  be 
attempted  to  apply  the  law  of  comparison  directly  to  the 
results  thus  obtained  by  the  model  experiments  it  will  be 
found  that  a  serious  error  is  introduced. 

The  reason  for  this  is  that  the  amount  of  power  required 
to  overcome  the  resistance  caused  by  friction  of  the  water 
in  contact  with  the  vessel  does  not  follow  this  law.  This 
is  largely  due  to  the  fact  that  the  particles  of  water  in 
contact  with  the  surface  of  the  vessel  are  dragged  along 
to  some  extent  in  the  direction  of  motion  so  that  the  fric- 
tion is  relatively  less  on  a  long  large  vessel  than  on  a  small 
short  model. 

It  is  possible,  however,  to  calculate  the  frictional  re- 
sistance separately,  by  using  the  results  that  have  been 
tabulated  from  many  experiments  on  surfaces  of  different 
characteristics,  lengths,  and  areas.  Thus  the  law  of  com- 
parison can  still  be  applied  by  making  the  proper  correc- 
tion for  friction  resistance.  The  method  is  briefly  as 
follows:  First,  the  model  is  towed,  and  its  total  resistance 
measured  and  recorded.  Second,  the  surface  or  friction 
resistance  of  the  model  is  calculated  and  taken  from  the 
total  resistance,  thus  giving  what  is  known  as  the  residual 
resistance  of  the  model.  Third,  from  the  residual  resistance 
of  the  model  by  means  of  the  law  of  comparison  the  cor- 
responding residual  resistance  of  the  ship  is  calculated. 


20  PRACTICAL  SHIP  PRODUCTION 

Fourth,  the  friction  resistance  of  the  ship  is  calculated  and 
added  to  the  residual  resistance  of  the  ship,  thus  giving  the 
total  resistance  of  the  ship.  Fifth,  the  power  required 
for  the  ship  is  then  readily  calculated. 

After  a  ship  has  been  given  proper  buoyancy,  stability, 
and  means  for  propulsion,  it  is  still  necessary  that  means 
be  provided  for  directing  her  from  place  to  place. 

4.  STEERING 

A  small  boat  or  canoe  can  be  steered  after  a  fashion  by  a 
paddle  or  by  oars,  and  large  vessels  may  be  kept  on  an 


Rudder  Stock  -f 


Rudder^  post 


VTiller 


Rudder^  y 
Rudder 


SIDE  ELEVATION       ^  PLAN 

FIG.  12.— Rudder. 

approximate  course  or  heading  by  manipulation  of  the 
sails  or  the  propellers  (where  more  than  one  are  provided). 
In  order,  however,  to  keep  any  moving  vessel  on  a  steady 
course  with  any  degree  of  accuracy,  it  is  necessary  to  pro- 
vide her  with  arudder.  Figure  12  shows  a  rudder  fitted  to 
the  stern  of  a  vessel.  The  rudder  is  a  flat  vertical  plate, 
hinged  to  the  stern  of  the  vessel,  and  capable  of  being 
rotated  horizontally  about  its  forward  edge  by  means  of  a 
lever  fitted  at  its  head,  called  a  tiller. 

As  the  ship  moves  ahead,  when  looking  in  the  direction 
of  her  motion,  that  side  of  the  ship  that  is  to  the  right  hand 
is  called  the  starboard  side,  and  that  to  the  left,  the  port 
side.  When  it  is  desired  to  change  the  direction  of  the 
ship's  motion  to  starboard,  the  tiller  (or  helm,  as  it  is  some- 
times called)  is  moved  to  port.  The  rudder  is  thus  brought 
to  starboard  and  offers  a  resistance  to  the  particles  of 


REQUIREMENTS  OF  SHIPS  21 

water  passing  the  ship  on  that  side.  The  resulting  pressure 
throws  the  ship's  stern  to  port  and  thus  alters  her  course 
to  starboard.  Similarly,  if  it  is  desired  to  change  the  ship's 
direction  to  port,  the  helm  is  put  to  starboard. 

The  tiller  on  all  but  very  small  vessels,  is  moved  by 
means  of  some  sort  of  a  mechanism  usually  actuated  by 
power,  known  as  a  steering  gear.  It  is  customary  to  fit  a 
wheel,  called  the  steering  wheel,  at  some  position  well  for- 
ward on  the  ship,  which  is  connected  by  suitable  ropes, 
rods,  shafting,  or  other  means,  to  the  tiller  or  to  an  engine 
that  actuates  the  tiller.  Where  a  steering  engine  is 
attached  to  the  tiller  the  connections  from  the  steering 
wheel  serve  merely  to  cause  the  steering  engine  to  function, 
no  power  being  applied  directly  to  the  tiller  by  the  connect- 
ing gear.  On  large  ships,  several  different  steering  wheels 
may  be  fitted  at  different  locations,  any  one  of  which 
may  be  used  for  steering  the  ship. 

The  vertical  post  forming  the  after  part  of  the  ship's 
stern  and  supporting  the  forward  edge  and  axis  of  the 
rudder,  is  called  the  rudder  post.  The  rudder  swings  about 
pintles,  which  are  vertical  pins,  usually  attached  to  lugs 
on  the  rudder,  fitting  into  gudgeons,  or  bearings  in  lugs 
which  are  usually  attached  to  or  form  a  part  of  the  rudder 
post. 

Several  different  forms  of  rudders  are  in  common  use,  the 
size  and  shape  depending  in  each  case  upon  the  type  of 
ship  and  her  size  and  speed.  War  ships  are  usually  fitted 
with  balanced  rudders,  in  which  a  portion  of  the  area  is 
placed  forward  of  the  axis,  which  is  extended  below  the 
rudder  post  for  that  purpose.  Rudders  of  the  ordinary 
type  similar  to  that  shown  in  Fig.  12  are  commonly  used 
for  merchant  vessels.  Rudders  of  both  the  balanced  and 
unbalanced  type  may  have  many  different  shapes  and 
sizes.  For  a  ship  which  must  turn  rapidly,  as  in  the  case 
of  most  war  ships,  a  much  larger  rudder  is  necessary  than 
for  merchant  vessels. 

The  principal  geometrical  requirements  of.  a  vessel  to 
make  her  suitable  as  a  means  for  over- water  transportation 


22  PRACTICAL  SHIP  PRODUCTION 

have  now  been  considered.  The  evolution  of  a  simple 
log  of  wood  hollowed  out,  shaped  and  enlarged  into  a 
ship,  and  then  provided  with  means  for  propulsion  and 
steering,  has  been  traced.  Little  or  no  consideration  has, 
however,  yet  been  given  to  what  was  inside  of  the  outer 
hull  or  skin  of  the  ship,  or  to  the  material  of  which  this 
hull  was  constructed. 

As  boats  and  canoes  were  increased  in  size  it  became 
necessary  to  make  them  structures  rather  than  simple 
hollowed  out  carved  logs.  Structural  strength  had,  then, 
to  be  considered. 

5.  STRENGTH 

Any  floating  body  is  subjected  to  certain  stresses  that 
must  be  taken  care  of  by  the  material  of  which  it  is  con- 
structed. For  a  floating  body  to  be  of  practical  use  in 
over-water  transportation,  as  has  been  seen,  it  must  be 
hollow.  The  assembled  material  of  which  such  a  floating 
body  is  made  up  is  collectively  known  as  the  hull. 

The  hull  may  be  considered  as  performing  two  functions : 

First. — To  keep  out  the  water,  and 

Second. — To  withstand  the  various  forces  exerted  by  the 
pressure  of  the  water  and  caused  by  the  weight  of  the 
structure  itself  and  the  other  weights  that  it  supports. 

If  the  hull  is  made  in  one  piece,  as  in  the  case  of  a  canoe 
carved  from  a  single  log,  its  thickness  must  be  compara- 
tively great  in  order  to  provide  the  necessary  strength  and 
rigidity.  This  is  shown  in  Fig.  13  (A),  which  represents  a 
cross  section  of  such  a  vessel.  If  a  large  enough  solid 
timber  could  be  obtained,  even  a  ship  might  be  considered 
as  so  fashioned.  Were  this  hull  made  of  concrete,  cast 
iron,  or  other  such  material,  the  same  reasoning  would 
apply,  but  it  can  readily  be  seen  that  for  large  vessels  the 
thickness  and  consequently  the  weight  would  be  practically 
prohibitive. 

The  hull  may,  however,  be  made  to  fulfil  the  two  func- 
tions mentioned  above  by  constructing  it  as  a  thin  skin 
or  membrane  supported  inside  at  suitable  intervals  by 


REQUIREMENTS  OF  SHIPS 


23 


framing.  In  Fig.  13  (B)  is  shown  a  cross  section  of  such  a 
vessel.  Here  the  outer  skin  consists  of  wood  planking, 
comparatively  thin,  which  is  supported  against  the  pressure 
of  the  water  by  transverse  frames.  Longitudinal  strength 
is  given  by  the  planking  itself,  and  also  by  a  timber  running 
along  the  bottom  of  the  centre  line,  known  as  a  keel.  The 
thicker  the  planking  is  made,  the  nearer  will  the  construc- 
tion of  (B)  of  Fig.  13  approach  that  of  (A),  and  consequently 
the  less  will  be  the  need  for  the  framing  and  the  smaller 
and  more  widely  spaced  may  the  frames  then  be.  Con- 
versely, the  thinner  the  planking  is  made,  the  greater 
will  be  its  need  for  support  from  the  frames. 

In  rough  weather  a  vessel  such  as  that  shown  in  Fig.  13  is 
liable  to  be  swamped  by  waves  coming  over  the  top,  and 


FIG.  13.— Solid  and  built-up  hulls. 

therefore  this  top  is  commonly  covered  by  a  deck  or  planked 
surface  supported  by  horizontal  framing,  usually  running 
athwartships,  called  deck  beams. 

The  planking  of  the  deck,  sides,  and  bottom  of  the  vessel 
may  be  considered  as  a  continuous  membrane  stretched 
over  a  frame  work  consisting  of  the  frames  and  beams. 
To  these  is  usually  added  certain  longitudinal  framing, 
inside  of  the  frames,  consisting  of  keelsons,  longitudinals, 
stringers,  girders,  etc.,  all  of  which  assist  in  supporting 
and  reinforcing  the  planking  and  furnishing  strength  and 
rigidity  to  the  structure  as  a  whole. 

The  most  satisfactory  material  for  use  in  the  construction 
of  ships  is  steel,  and  owing  to  its  great  strength,  much  less 
volume  needs  to  be  devoted  to  the  hull  itself,  thus  leaving 


24  PRACTICAL  SHIP  PRODUCTION 

more  space  available  for  cargo,  passengers,  machinery, 
fuel,  etc.  The  planking  shown  in  Fig.  13  (B)  is  replaced 
by  thin  steel  plating,  and  instead  of  the  massive  wooden 
frames,  comparatively  small  steel  bars  of  various  cross 
sections  are  used. 

Strength  must  be  provided  for  a  ship  in  three  ways; 

1.  Strength  for  the  ship  as  a  whole; 

2.  Local  strength; 

3.  Strength  partaking  somewhat  of  the  nature  of  both 
1  and  2. 

Strength  of  the  Ship  as  a  Whole. — In  the  first  case  the 
ship  must  be  considered  as  a  large  girder  loaded  with 
various  weights,  some  concentrated  and  some  distributed 
throughout  its  length  and  breadth,  and  supported  by  the 
buoyancy  or  upward  pressure  of  the  water,  which  may  vary 
at  all  points  in  the  length  on  account  of  the  under  water 
form  of  the  ship.  This  girder  strength  of  the  ship  must  be 
considered  both  transversely  and  longitudinally,  although 
for  ships  as  ordinarily  constructed,  transverse  strength 
is  usually  greater  than  longitudinal  strength  and  does  not 
require  so  much  investigation. 

In  addition  to  the  stresses  caused  by  the  loading  of  the 
vessel  and  the  forces  of  buoyancy,  it  is  necessary  to  consider 
the  stresses  that  are  set  up  when  the  ship  is  passing  through 
large  waves.  These  stresses  are  caused  by  forces  that  are 
both  static  and  dynamic,  the  former  being  due  to  the  form 
of  the  waves  and  the  latter  being  due  to  the  motion  of  the 
vessel  through  the  waves. 

It  is  usually  customary  when  designing  a  ship,  to  make  an 
investigation  of  her  girder  strength  by  assuming  that  she 
is  poised  either  on  the  crest  or  in  the  trough  of  a  wave 
equal  in  length  to  her  own  length,  and  on  this  assumption 
to  calculate  the  resulting  stresses.  For  ordinary  ships 
the  stresses  thus  obtained  will  be  greater  than  those  that 
may  be  expected  to  be  developed  in  actual  service,  and  the 
excess  thus  allowed  for  in  this  calculation,  which  takes 
account  of  static  forces  only,  is  assumed  to  be  sufficient  to 
offset  the  stresses  caused  by  dynamic  forces.  This  assump- 


REQUIREMENTS  OF  SHIPS 


25 


tion  is  based  upon  the  fact  that  ordinary  sized  ships  seldom, 
if  ever,  encounter  such  large  waves. 

The  upper  half  of  Fig.  14  shows  a  ship  poised  in  the  trough 
of  a  wave  with  a  crest  at  each  end.  In  this  case  some 
of  the  support  normally  given  by  the  water  is  taken  away 
from  the  middle  portion  of  the  ship  and  some  is  added  at 
each  end.  The  vessel  thus  has  a  tendency  to  droop  in  the 
middle.  This  is  called  sagging.  When  the  crest  of  the  wave 
comes  at  the  mid-length  of  the  ship,  as  shown  in  the  lower 
half  of  Fig.  14,  the  reverse  is  the  case,  and  the  ends  tend 
to  droop.  This  is  called  hogging. 

Calculations  for  longitudinal  strength  may  be  made  both 
for  the  condition  in  still  water  and  with  the  ship  poised  on 


Sagging 


Hogging 


FIG.  14. — Sagging  and  hogging. 

either  the  crest  or  the  trough  of  a  wave  equal  in  length  to 
its  own  length.  Without  going  into  great  detail,  the  method 
pursued  may  be  described  as  follows : 

1.  From    a    general    consideration    of   the    proportions 
and  form  of  the  ship  and  the  locations  of  the  large  important 
weights,  a  decision  is  reached  as  to  whether  the  most  serious 
strains  experienced  will  be  those  of  hogging  or  those  of 
sagging,  and  the  case  producing  the  most  serious  strains 
is  selected. 

2.  The  surface  of  a  trochoidal  wave  of  the  same  length  as 
the  ship  and  of  a  height  equal  to  one-twentieth  of  its  length 
is  applied  to  the  plans  of  the  ship,  the  position  of  the  wave 
surface  being  so  adjusted  that  the  volume  cut  by  it  from 


26 


PRACTICAL  SHIP  PRODUCTION 


the  ship  is  exactly  the  same  as  the  immersed  volume  of 
the  ship  when  floating  in  still  water. 

3.  Calculations  are  then  made,  by  means  of  which  a  curve 
is  constructed  with  the  ship's  length  as  a  base  and  with 
ordinates   representing   the    upward    force    of   buoyancy 
for  each  point  in  the  ship's  length*     These  calculations 
are  based  upon  the  principle  previously  explained,  that 
the  upward  pressure  on  a  floating  body  is  equal  to  the 
weight  of  the  water  displaced  by  that  body. 

4.  On  this  same  base  line,  from  detailed  calculations  of 
the  weights  and  locations  of  the  members  and  various 
parts  that  make  up  the  ship  and  all  that  she  carries, 
another  curve  is  drawn,  each  ordinate  of  which  represents 

of  Bending  Moments 
rve  of  Weight* 
Curve  of  Shearing  Forces 


Length  of  Ship,  to  Scale 


Bow 


Curve  of  Buoyancy 


I  \Curve  of  Load 


FIG.  15.  —  Curves  for  strength  calculation. 

the  weight  with  which  the  ship  is  loaded  at  the  point  repre- 
sented by  the  corresponding  abscissa.  These  two  curves  may 
look  something  like  the  curves  in  Fig.  15,  which  are  marked 
"  curve  of  buoyancy"  and  "  curve  of  weights"  respectively. 
These  curves  are  drawn  for  a  ship  poised  with  the  centre 
of  its  length  at  the  trough  of  the  wave,  as  will  be  seen  by  the 
general  shape  of  the  curve  of  buoyancy.  It  will  be  noted 
that  ordinates  representing  weights  are  considered  as 
positive  and  those  representing  the  forces  of  buoyancy 
as  negative,  since  they  act  in  opposite  directions. 

5.  A  third  curve  is  obtained  by  subtracting  the  ordinates 
of  the  buoyancy  curve  from  the  corresponding  ordinates 
of  the  weight  curve.  This  third  curve  is  called  the  curve 


REQUIREMENTS  OF  SHIPS  27 

of  load,  and  represents  the  resultant  of  the  vertical  forces  of 
weight  and  buoyancy  at  each  point.  It  should  be  noted 
that  for  equilibrium  the  area  of  the  weight  and  buoyancy 
curves  must  be  equal  and  that  the  area  of  the  load  curve 
above  the  horizontal  axis  must  be  exactly  equal  to  its  area 
below  that  axis. 

6.  By  the  successive  integration  of  the  load  curve  and  its 
integral  curve  are  obtained  the  curves  of  shearing  force 
and  bending  moment,  as  shown  in  the  figure. 

7.  The  maximum  bending  moment  and  the  point  at 
which  it   occurs   are   then  determined,   and   calculations 
for  the  strength  of  the  ship  at  this  point  are  made  to  see 
that  this  strength  is  sufficient.     This  is  done  by  finding 
the   moment   of  inertia  of   this   section   and   calculating 
the  maximum  fiber-stress,   making  use  of  the  ordinary 

T)          7W 

beam  formula:   —  =— ^-*     If   the   stress   is   found  to  be 
y        I 

excessive,  the  size  of  some  of  the  members  must  be  in- 
creased in  order  to  reduce  it,  and  a  second  calculation 
made  to  see  that  a  satisfactory  maximum  stress  has  been 
obtained. 

A  similar  method  might  be  pursued  in  the  investigation 
of  the  transverse  strength  of  a  ship  if  desired.  But  this 
is  not  usually  found  to  be  necessary,  as  the  transverse 
strength  is  usually  more  than  ample.  In  war  ships  and 
ships  of  special  type,  however,  such  calculations  may  have 
to  be  made. 

Transverse  strength  may  also  be  investigated  where 
special  conditions  require  this  to  be  done,  by  means  of  the 
"  Principle  of  Least  Work." 

Local  Strength. — Local  strength  must  be  provided  in 
special  cases  to  meet  special  needs.  For  example,  at  the 
bow  of  the  ship  there  is  a  tendency  for  the  plating  to  move 
in  and  out  when  the  ship  is  in  a  seaway.  Such  movement, 
called  panting ',  is  provided  against  by  means  of  special 
stiffening,  such  as  ram  plates,  breast  hooks,  panting  stringers, 
etc.  Other  cases  where  local  strength  is  required  are  gun 
and  turret  foundations,  supports  for  boat  cranes  and 


28  PRACTICAL  SHIP  PRODUCTION 

davits,  masts,  engines,  boilers,  etc.,  i.e.,  heavy  concentrated 
weights  or  fittings  that  receive  heavy  sudden  loads  or 
shocks. 

Strength,  Partly  for  Ship  as  Whole  and  Partly  Local.— 
It  is  difficult  to  make  an  exact  distinction  between  local 
strength  and  strength  of  the  ship  as  a  whole  in  certain 
cases.  For  example,  the  forces  of  the  rudder  and  pro- 
pellers must  be  transmitted  to  the  whole  hull.  Also  if 
the  vessel  is  towed  or  is  towing,  the  deck  fittings  to  which 
the  tow-line  is  attached  must  transmit  practically  the 
entire  stress  to  the  whole  ship.  The  same  applies  to  stresses 
transmitted,  in  sailing  ships,  by  the  masts,  and  rigging. 

In  general,  it  must  be  remembered  that  all  these  stresses 
must  be  gradually  transmitted  from  the  member  receiving 
the  full  force,  to  the  remainder  of  the  hull.  There  should 
be  no  sudden  break  in  strength,  but  as  the  strength  is 
reduced  from  its  maximum  to  its  minimum,  it  should  be 
tapered  off  gradually.  Any  sudden  break  in  strength  causes 
a  point  of  weakness,  and  is  liable  to  cause  failure  in  an 
emergency.  This  general  rule  applies  to  structural  design 
throughout. 

6.  ENDURANCE 

The  next  quality — which  is  of  great  importance  only  in 
the  case  of  seagoing  vessels — is  endurance.  If  a  ship  is  to 
be  suitable  for  voyages  of  any  great  length  she  must  carry 
enough  coal  or  other  fuel  to  propel  her  for  the  required 
distances,  and,  if  propelled  by  steam  power,  must  carry 
enough  fresh  water  for  the  boilers,  or  must  be  provided 
with  evaporators  to  convert  salt  water  into  fresh  water 
while  at  sea.  She  must  also  have  space  to  carry  sufficient 
food  and  fresh  water  for  all  persons  on  board  during  the 
trip. 

The  amount  of  space  and  weight  that  must  be  devoted 
to  fuel  and  other  consumable  weights  depends  upon  the 
service- for  which  the  ship  is  intended.  It  should  always 
be  carefully  considered  in  the  design.  By  far  the  largest 
percentage  of  these  weights  is  that  required  for  fuel.  In 


REQUIREMENTS  OF  SHIPS  29 

this  connection  it  is  very  necessary  to  know  whether  the 
vessel  can  secure  fuel  at  each  of  her  terminal  ports,  or 
ports  of  call,  or  whether  she  can  coal  (or  oil)  only  at  her 
home  port.  It  is  also  usually  important  that  she  does  not 
carry  an  unnecessary  amount  of  fuel  since  this  cuts  down 
the  space  available  for  cargo,  passengers,  and  other  uses, 
and  therefore  limits  the  utility  of  the  ship. 

In  designing  a  ship,  after  the  type  and  size  of  the  engines 
and  boilers  have  been  determined,  and  the  kind  of  fuel 
that  is  to  be  used  has  been  decided  upon,  the  amount  of 
space  that  must  be  assigned  to  fuel  is  calculated  from  data 
on  the  fuel  consumption  that  may  be  expected  and  the 
length  of  the  greatest  voyage  that  it  is  intended  the  ship 
shall  be  capable  of  making.  Data  regarding  the  probable 
fuel  consumption  is  obtained  from  the  results  of  past 
experience  in  other  vessels. 

7.  UTILITY 

Although  a  vessel  may  have  all  the  qualifications  that 
have  already  been  described,  there  is  still  one  more  that 
must  be  provided.  Arrangements  must  be  made  to  make 
the  vessel  suitable  for  the  use  to  which  she  is  to  be  put. 
These  arrangements  include  the  following: 

1.  Living  Accommodations  for  Officers  and  Crew. — The 
complement  of  the  ship,  which  includes  the  men  charged 
with  the  care  and  operation  of  the  engines,  boilers,  and  other 
auxiliary  machinery,  the  steering  and  navigating  of  the 
ship,  her  cleanliness,  care,  and  upkeep,  and  the  other  duties 
necessary  for  her  proper  maintenance  and  operation,  must 
be    suitably   sheltered   and   fed.     This   requires   sleeping 
accommodations,  eating  and  toilet  facilities,  and  more  or 
less  elaborate  systems  of  lighting,   heating,   ventilation, 
plumbing,  and  refrigeration. 

2.  Space  for  Carrying  Passengers,  or  Cargo,  or  Fuel,  or 
Space  Necessary  for  any  Special  Service  for  which  the 
Vessel  is  to  be  Used. — Special  staterooms,  dining  saloons, 
galleys,  etc.,  are  necessary  for  passenger  ships  in  addition 


30  PRACTICAL  SHIP  PRODUCTION 

to  those  necessary  for  a  ship's  complement,  and  must  also 
have  even  more  elaborate  lighting,  heating,  ventilating, 
and  similar  systems  than  those  provided  for  the  crew. 

For  vessels  designed  to  carry  cargo,  large  holds  and  other 
cargo  spaces  fitted  with  special  large  openings,  and  derricks 
and  hoisting  engines  for  loading  and  unloading  cargo  must 
be  provided.  In  case  the  cargo  is  of  a  special  type,  such 
as  oil  or  other  liquids  carried  in  bulk,  or  fruits,  meats,  or 
other  perishable  goods,  special  arrangements  must  be 
made  for  stowing  and  handling  it. 

In  the  case  of  warships,  arrangements  must  be  made  for 
turrets,  barbettes,  guns,  torpedoes,  mines,  armor,  maga- 
zines, etc.,  together  with  the  necessary  machinery  for 
controlling,  operating  and  supplying  the  battery. 

3.  Auxiliary  Requirements. — All  ships  must  have  means 
for  anchoring  and  mooring,  boats,  and  means  for  hoisting 
and  lowering  them,  gangways,  ladders,  and  other  means  for 
ingress  and  egress,  means  for  signalling  or  communication 
with  the  shore  or  with  other  ships,  means  for  pumping 
water  from  one  compartment  to  another,  protection 
against  fire,  sails  (to  some  extent,  at  least,  in  case  of  break- 
down of  the  main  engines),  special  navigational  apparatus, 
various  means  for  interior  communication,  and  many  other 
special  arrangements  too  numerous  to  mention. 

All  of  these  arrangements  affecting  the  utility  of  the  ship 
vary  with  her  size  and  the  service  for  which  she  is  designed, 
but  all  are  very  important  and  must  be  carefully  considered 
during  the  course  of  the  design. 

RECAPITULATION 

The  principal  requirements  of  all  ships  are: 

1.  Buoyancy. 

2.  Stability. 

3.  Propulsion. 

4.  Steering. 

5.  Strength. 

6.  Endurance. 

7.  Utility. 


CHAPTER  II 

GENERAL  DESCRIPTION  OF  SHIPS 
1.  FORM 

The  Lines. — The  outer  form  of  a  ship  is  a  curved  undevel- 
opable surface.  It  can  be  represented  geometrically  by 
fixing  the  locations  in  space  of  points  on  this  surface.  The 
greater  the  number  of  points  taken  the  more  accurately 
will  the  surface  be  determined.  For  convenience  it  is 
customary  to  locate  these  points  by  means  of  co-ordinates 
or  "offsets"  measured  at  right  angles  to  the  following 
three  planes: 

1.  A  vertical  longitudinal  plane  dividing  the  ship  into  two 
symmetrical  halves.     Ordinates  perpendicular  to  this  plane 
are  called  half -breadths. 

2.  A  horizontal  plane  parallel  to  the  surface  of  the  water 
and  intersecting  the  first  plane  in  a  line  called  the  base  line. 
Ordinates  measured  vertically  up  from  this  horizontal  plane 
are  called  heights. 

3.  A  plane  at  right  angles  to  each  of  the  first  two  planes, 
and  for  convenience  often  taken  at  the  mid-length  of  the 
ship.     The  intersection  of  this  plane  with  the  ship's  surface 
is    called    the    midship    section    or    dead  flat.     Ordinates 
perpendicular  to  this  plane  are  thus  measured  longitudi- 
nally and  are  usually  expressed  as  distances  forward  or  aft 
of  the  midship  section,  depending  upon  whether  they  are 
measured  toward  the  bow  or  toward  the  stern  of  the  ship. 
(The  midship  section  is  usually  designated  by  the  symbol 

38C). 

If  the  surface  of  the  ship  be  considered  as  cut  by  planes 
parallel  to  each  of  these  three  reference  planes,  then  the 
intersections  of  the  planes  will  be  curved  lines  which 
may  be  projected  upon  the  three  reference  planes,  the 
projection  of  any  particular  intersection  appearing  as  a 

31 


32  PRACTICAL  SHIP  PRODUCTION 

straight  line  on  two  of  the  planes  and  as  a  curved  line 
on  the  third. 

A  drawing  consisting  of  such  projections  is  called  the 
lines  of  the  ship,  and  the  ^projections  on  the  first  plane 
make  up  what  is  usually  called  the  sheer  or  profile  plan; 
on  the  second  plane,  the  'half -breadth  plan;  and  on  the 
third,  the  body  plan.  Sueh  a  set  of  lines  is  shown  in 
Fig.  16. 

Intersections  of  the  ship's  surface  by  planes  parallel 
to  the  third  plane  are  called  cross  sections.  These  are 
marked  in  Fig.  16  by  numbers  2  to  10  inclusive. 

Intersections  of  the  surface  by  planes  parallel  to  the 
second  plane  are  called  water  lines.  These  are  marked  in 
Fig.  16:  W.  L.  "A",  L.  W.I,,  2  W.  L.,  3  W.  L.,  4  W.  L. 
"L.  W.  L."  is  the  usual  abbreviation  for  load  water  line, 
which  is  the  intersection  of  the  surface  of  the  ship  by  the 
plane  of  the  surface  of  the  water  when  the  ship  is  floating 
with  her  designed  load  on  board  and  is  perfectly  upright 
in  the  water,  or  with  the  base  line  horizontal. 

Intersections  of  the  surface  of  the  ship  by  planes  parallel 
to  the  first  plane  are  called  bow  and  buttock  lines  or  simply 
buttocks.  One  buttock  only  is  shown  in  Fig.  16,  but 
several  are  usually  drawn. 

For  convenience  in  drawing  the  lines  it  is  also  customary 
to  take  one  or  more  intersections  of  the  ship's  surface 
by  a  plane  or  planes  perpendicular  to  the  midship  section 
plane  but  at  an  angle  with  each  of  the  other  two.  Such 
intersections  are  called  diagonals,  and  appear  as  straight 
lines  in  only  one  plan  and  as  curves  in  the  other  two.  A 
diagonal  is  usually  shown  projected  in  the  sheer  plan, 
but  expanded,  or  in  its  true  shape,  in  the  half -breadth  plan. 
One  diagonal  only  (the  bilge  diagonal)  is  shown  in  Fig.  16. 

Certain  lines  of  a  ship's  form  (of  which  only  one — the 
line  of  the  deck  at  side — is  shown  in  Fig.  16)  have  curvature 
in  all  three  dimensions  and  therefore  appear  as  curves  in 
all  three  plans. 

The  drawing  of  the  lines  of  a  ship  is  simply  a  problem  of 
descriptive  geometry.  All  offsets  must  appear  in  their 


GENERAL  DESCRIPTION  Of  SHIPS 


33 


34  PRACTICAL  SHIP  PRODUCTION 

actual  length  in  two  of  the  three  plans.  For  example, 
all  breadths  can  be  measured  in  both  the  half-breadth  and 
the  body  plan.  (They  appear  as  points  in  the  sheer  plan.) 
During  the  process  of  drawing  the  lines  it  is  necessary 
that  all  such  offsets  be  made  to  agree,  in  each  case,  in 
the  two  plans,  and  at  the  same  time  the  curves  or  sections 
of  the  ship's  form  that  are  determined  by  these  offsets 
must  be  regular  smooth  curves.  The  process  of  thus 
adjusting  the  various  offsets  is  called  fairing  the  lines,  and 
when  it  has  been  properly  done,  all  the  curves  will  be 
smooth  and  regular  and  are  then  said  to  be  fair.  A  surface 
or  curve  is  thus  spoken  of  as  "fair"  when  it  has  a  smooth 
curvature — free  from  humps  or  hollows. 

Definitions  Applying  to  a  Ship's  Form. — There  are  certain 
terms,  dimensions,  and  names  of  parts  that  apply  to  'ships' 
forms  in  particular.  These  are  used  frequently  both  during 
the  design  and  construction  of  ships,  and  a  knowledge  of 
their  meaning  is  essential  to  all  shipbuilders.  A  few  of 
these  have  already  been  explained  in  the  preceding  pages 
and  some  are  indicated  in  the  lines  of  the  ship  represented 
in  Fig.  16,  but  in  order  to  make  the  subject  of  form  complete 
they  will  be  included  in  the  definitions  given  below: 

1.  Directions  on  a  Ship. — The  end  of  a  ship  that  cuts 
the  water  when  a  ship  moves  ahead  is  called  the  bow. 
The  other  end  is  called  the  stern.  The  bow  and  stern  form 
the  extremities  of  the  ship's  length.  Distances  measured 
in  the  general  direction  between  bow  and  stern  are  said  to 
be  measured  in  a  fore  and  aft  direction,  or  longitudinally. 
Distances  measured  at  right  angles  to  this  direction, 
and  horizontally,  are  said  to  be  measured  athwartships, 
transversely,  or  in  an  athwartship  or  transverse  direction. 
The  term  amidships  means  at  or  near  the  centre  of  the  ship, 
considered  either  in  the  fore  and  aft  or  in  the  athwartship 
direction.  Inboard  means  toward  the  centre,  and  outboard 
toward  the  side  of  the  ship.  The  terms  fore  and  forward 
apply  to  parts  of  the  ship  that  are,  in  general,  at,  near,  or 
toward  the  bow,  while  the  terms  aft  and  after  apply  to 
parts,  in  general,  at,  near,  or  toward  the  stern.  For  ex- 


GENERAL  DESCRIPTION  OF  SHIPS  35 

ample,  the  fore-body  of  the  ship  is  the  portion  of  her  form 
that  is  forward  of  the  midship  section,  or,  if  the  ship  has  a 
constant  cross  section  for  a  portion  of  her  length  amidships, 
that  portion  forward  of  this  constant  cross  section.  SimiT 
larly,  the  afterbody  is  the  portion  of  the  ship's  form  aft  of 
this  parallel  middle  body,  or  of  the  midship  section  in  case 
no  portion  of  her  length  is  parallel  sided.  When  looking 
from  the  stern  toward  the  bow,  that  side  of  the  ship  that  is 
to  the  right  hand  is  called  the  starboard  side  and  that  to  the 
left  hand,  the  port  side.  When  steaming  at  night,  ships 
usually  show  a  green  light  on  the  starboard  side  and  a  red 
(port  colored)  light  on  the  port  side.  Distances  measured 
vertically  are  spoken  of  as  heights  or  depths.  When  speak- 
ing of  a  part  of  a  ship  under  any  point  of  reference  it  is  said 
to  be  below — instead  of  using  the  landsman's  "down  stairs." 
The  term  on  deck  usually  refers  to  locations  on  the  highest 
or  upper  deck,  the  decks  being  nearly  (but  not  quite) 
horizontal  surfaces  corresponding  to  the  floors  of  a  building 
on  shore. 

2.  Reference  Lines  and  Planes. — The  keel  line  is  the  line 
of  the  fore  and  aft  member  running  along  the  centre  line 
of  the  ship  at  its  lowest  part.  The  base  line  is  the  inter- 
section of  the  central  longitudinal  vertical  plane  of  the 
ship  with  a  horizontal  plane  through  the  top  of  the  keel  at 
the  midship  section  (in  some  cases  the  keel  line  and  the 
base  line  are  the  same).  The  load  water  line  (usually 
marked  L.  W.  L.)  is  the  term  applied  to  the  line  in  the 
lines  of  the  ship  which  represents  the  intersection  of  the 
ship's  form  with  the  plane  of  the  surface  of  the  water  when 
the  ship  is  floating  with  her  designed  load  on  board. 
This  term  is  somewhat  of  a  misnomer  since  it  is  really 
applied  to  the  load  water  plane  rather  than  to  the  load 
water  line.  It  is  sometimes  applied  to  the  trace  of  the 
plane  of  the  water  with  the  central  vertical  plane,  and 
sometimes  to  the  trace  of  the  water  surface  plane  with  the 
transverse  plane  at  the  mid-length  of  the  ship,  and  also 
to  the  projection  of  the  intersection  of  the  water  surface 
with  the  ship's  surface  on  the  horizontal  plane.  The 


36  PRACTICAL  SHIP  PRODUCTION 

forward  perpendicular  is  the  vertical  line  through  the 
intersection  of  the  forward  side  of  the  stem  with  the  load 
water  plane.  The  after  perpendicular  is  the  vertical  line 
through  the  intersection  of  the  after  side  of  the  stern  post 
with  the  load  water  plane.  The  midship  section  (55!)  is 
the  intersection  of  the  ship's  form  with  a  transverse  ver- 
tical plane  midway  between  the  forward  and  the  after 
perpendiculars. 

NOTE. — These  above-mentioned  lines  and  planes  are 
shown  in  Fig.  16,  in  which  they  should  be  carefully  noted. 

3.  Molded  Dimensions. — The  molded  surface  of  a  ship 
is  the  surface  passing  through  the  outer  edges  of  all  the 
framing  or  the  inner  surface  of  the  planking  or  plating 
which  forms  the  outer  skin.  It  is  the  surface  represented 
by  the  lines.  The  length  between  perpendiculars  (L.  B.  P.) 
is  the  distance  between  the  forward  and  the  after  per- 
pendiculars. The  length  over  all  (L.  O.  A.)  is  the  length 
between  the  extreme  forward  and  after  points  of  the  ship 
measured  parallel  to  the  base  line.  The  molded  breadth 
is  the  maximum  transverse  breadth  of  the  molded  surface 
at  the  midship  section.  The  molded  depth  is  the  vertical 
distance  from  the  base  line  to  the  line  of  the  main  deck  at 
side  at  the  midship  section.  The  draft  is  the  vertical 
distance  between  the  bottom  of  the  keel  and  the  water 
line  at  which  the  ship  is  considered  as  floating.  When 
measured  at  the  forward  end  of  the  ship  the  draft  is  called 
the  draft  forward,  and  when  measured  aft,  is  called  the 
draft  aft.  The  arithmetical  mean  of  the  draft  forward 
and  the  draft  aft  is  called  the  mean  draft.  The 
difference  between  the  draft  forward  and  the  draft  aft  is 
called  the  trim.  When  the  draft  aft  is  greater  than  the 
draft  forward,  the  vessel  is  said  to  trim  by  the  stern.  When 
the  reverse  is  the  case  she  is  said  to  trim  by  the  bow.  When 
a  ship  is  designed  to  float  normally  with  a  greater  draft 
aft  than  forward,  the  difference  in  the  two  drafts  is  called 
the  drag.  Load  draft  is  the  draft  of  the  ship  when  floating 
at  the  load  water  line.  Extreme  draft  is  the  vertical  dis- 
tance of  the  lowest  point  of  the  ship  below  the  surface  of 


GENERAL  DESCRIPTION  OF  SHIPS  37 

the  water.  Freeboard  is  the  height  of  the  ship  above  the 
water's  surface,  or  it  is  the  difference  between  the  moulded 
depth  and  the  draft.  Rise  of  bottom,  or  rise  of  floor,  or 
dead  rise  are  all  expressions  meaning  the  amount  that  the 
straight  portion  of  the  bottom  rises  in  the  half-beam  of 
the  ship.  Tumble  home  is  the  amount  that  the  side  of  -the 
ship  is  nearer  to  the  centre  line  at  the  top  than  at  the 
level  of  greatest  width.  Flare  is  the  opposite  of  tumble 
home.  (Cross  section  No.  2  in  Fig.  16  has  a  flare  while 
No.  5  has  a  tumble  home.)  Camber  (also  called  crown 
or  round  up)  is  the  distance  that  the  centre  of  the  surface 
of  a  deck  is  above  its  side.  Instead  of  being  flat  plane 
surfaces  decks  usually  are  curved  surfaces  of  such  form 
that  a  transverse  vertical  section  will  be  a  curve  higher  at 
the  centre  than  at  the  sides.  This  transverse  curvature 
is  called  the  camber  and  is  usually  expressed  as  the  distance 
that  the  arc  is  above  the  chord  for  a  given  beam.  (See 
Fig.  17.)  Sheer  is  the  term  applied  to  the  fore  and  aft 
curvature  of  a  deck.  Decks  usually  have  a  longitudinal 
curvature  as  well  as  a  transverse  curvature,  but  in  this 
case  the  ends  are  higher  than  the  centre.  (Note  sheer  of 
deck  at  side  in  Figs.  16  and  17.) 

NOTE. — The  various  terms  above  described  are  illus- 
trated in  Fig.  16,  in  which  they  should  be  carefully  noted. 

4.  Terms  Referring  to  Form. — A  few  of  the  most  com- 
monly used  terms  referring  to  form  of  ships  are  illustrated 
in  Fig.  17,  and  are  defined  below. 

The  entrance  is  the  forward  under  water  portion  of  the 
ship  at  and  near  the  bow,  which  enters  the  water  first  as  the 
ship  moves  ahead.  The  run  is  the  portion  of  the  ship's 
form  under  water  at  and  near  the  stern  which  last  leaves  the 
water  as  the  ship  moves  ahead.  The  stem  is  the  forward 
edge  of  the  bow  which  cuts  the  water  when  the  ship  moves 
ahead.  The  stern  post  is  the  vertical  post  at  the  after  end  of 
the  under  water  portion  of  the  ship.  The  bottom  is  the  flat 
or  nearly  flat  portion  of  the  ship's  surface  extending  out- 
board on  each  side  from  the  keel  and  usually  sloping  slightly 
upward.  The  term  " bottom"  is  also  applied,  in  a  general 


38 


PRACTICAL  SHIP  PRODUCTION 


GENERAL  DESCRIPTION  OF  SHIPS  39 

sense,  to  all  of  the  ship's  surface  below  the  water  line.  The 
sides  are  the  vertical  or  nearly  vertical  portions  of  the  ship's 
surface.  Bilge  is  the  term  applied  to  the  curved  portion 
of  the  ship's  surface  between  bottom  and  side.  This  is 
also  sometimes  called  the  turn  of  the  bilge.  Fore  foot  is  the 
term  applied  to  the  after  lower  end  of  the  stem  or  the 
part  of  the  stem  that  connects  with  the  keel.  Dead  wood 
is  a  term  applied  to  the  portion  of  the  hull  at  the  junction 
of  the  stern  and  stern  post  with  the  keel.  The  boss  is  the 
curved  swelling  portion  of  the  ship's  surface  around  the 
propeller  shaft  or  shafts.  Knuckle,  in  general,  is  the  term 
applied  to  any  line  forming  the  intersection  of  two  curved 
surfaces,  and  in  particular,  to  the  intersection  of  the 
upper  nearly  vertical  portion  of  the  ship's  surface  above 
water  at  the  extreme  stern  with  the  lower  more  sloping 
portion  of  the  stern.  Quarter  is  the  curved  portion  of 
the  ship  on  either  side  at  the  extreme  stern.  Bow  (besides 
meaning  the  forward  end  of  the  ship)  is  applied  to  the 
curved  forward  portion  of  the  ship  on  either  side  of  the 
stem.  Bulwarks  is  that  portion  of  the  ship's  surface 
between  the  rail  and  the  highest  complete  deck,  forming  an 
inclosure  or  railing  around  the  perimeter  of  that  deck. 
Rail  is  the  upper  edge  of  the  bulwarks.  Counter  is  the 
term  applied  to  that  portion  of  the  ship's  surface  between 
the  knuckle  and  the  water  line  near  the  stern.  The  rudder 
post  is  the  vertical  post  at  the  stern  to  which  is  hinged  the 
rudder.  In  sailing  ships  or  ships  with  twin  or  quadruple 
screw  propellers  it  is  also  the  stern  post.  Propeller  post 
is  the  vertical  post  at  the  stern  of  a  single  or  triple  screw 
vessel  through  which  passes  the  shaft  of  the  centre  propeller. 
5.  Coefficients  of  Form. — The  form  of  a  ship  is  deter- 
mined from  a  number  of  considerations.  First  the  volume 
of  the  under  water  form  must  be  sufficient  to  displace  an 
amount  of  water  equal  in  weight  to  the  total  weight  of 
the  ship  and  all  that  she  carries.  Then  in  order  to  reduce 
resistance  and  to  provide  a  good  run  of  water  to  the  pro- 
pellers the  entrance  and  run  must  be  tapered.  Also,  the 
form  must  be  so  proportioned  as  to  give  the  requisite  sta- 


40  PRACTICAL  SHIP  PRODUCTION 

bility.  In  some  cases  the  draft  is  limited  by  the  depth  of  the 
waters  through  which  the  ship  must  pass.  These  various 
requirements  are  usually  somewhat  conflicting,  and  the 
final  determination  of  the  form  of  the  ship  is  more  or  less 
in  the  nature  of  a  compromise.  For  example,  if  in  an 
endeavor  to  reduce  resistance,  the  ship's  form  be  made 
too  narrow  and  fine  or  sharp,  sufficient  stability  may  not 
be  obtained.  In  providing  sufficient  volume  to  give  the 
desired  displacement  the  lines  may  be  made  so  full  or 
" bulging"  as  to  give  an  unduly  high  resistance. 

It  will  be  found  that  certain  classes  of  vessels  have 
forms  that  are  very  nearly  the  same,  and  as  large  numbers 
of  such  ships  have  already  been  built  and  put  into  service 
it  is  possible  to  compare  these  with  contemplated  ships. 
For  this  purpose  it  is  convenient  to  refer  to  certain  coeffi- 
cients and  ratios,  among  the  most  common  of  which  are 
the  following:  block  coefficient  of  fineness,  load  water-line 
coefficient,  midship  section  coefficient,  longitudinal  pris- 
matic coefficient,  vertical  prismatic  coefficient,  ratio  of 
length  to  beam,  ratio  of  beam  to  draft. 

The  block  coefficient  of  fineness  (usually  called  simply  the 
block  coefficient)  is  the  ratio  of  the  under  water  volume  of 
the  ship  to  the  volume  of  the  circumscribing  rectangular 
parallelepiped,  or  the  rectangular  solid  of  the  same  length 
as  the  L.  W.  L.  and  with  width  equal  to  the  ship's  beam  and 
depth  equal  to  the  ship's  draft.  The  load  water-line 
coefficient  is  the  ratio  of  the  area  of  the  load  water  line  to 
the  circumscribing  rectangle.  The  midship  section  coef- 
ficient is  the  ratio  of  the  area  of  that  portion  of  the  mid- 
ship section  which  lies  below  the  load  water  line  to  the 
area  of  the  circumscribing  rectangle.  The  longitudinal 
prismatic  coefficient  is  the  ratio  of  the  under  water  volume 
of  the  ship  to  the  volume  of  a  cylinder  having  for  length 
the  length  of  the  L.  W.  L.  and  for  a  base  the  immersed  mid- 
ship section  of  the  ship.  The  vertical  prismatic  coefficient  is 
the  ratio  of  the  under  water  volume  of  the  ship  to  the  volume 
of  a  cylinder  having  for  height  the  draft  of  the  ship,  and 
for  base  the  area  of  the  load  water  line.  The  terms  ratio 


GENERAL  DESCRIPTION  OF  SHIPS  41 

of  length  to  beam  and  ratio  of  beam  to  draft  are  self- 
explanatory. 

A  knowledge  of  these  various  coefficients  gives  a  general 
idea  of  the  form  and  type  of  the  vessel's  hull.  If  the  value 
of  the  coefficient  is  high,  the  lines  are  said  to  be  full,  and 
if  relatively  low,  the  lines  are  said  to  be  fine.  The  ratio 
of  length  to  beam  is  an  index  of  the  fineness  of  the  ship 
longitudinally,  the  greater  this  ratio  being,  the  greater 
being  the  fineness  and  consequently  the  speed  that  can  be 
obtained,  other  things  being  unchanged.  The  ratio  of 
beam  to  draft  is,  in  general,  an  index  of  the  transverse 
stability. 

As  an  example  of  the  variation  in  values  of  the  block 
coefficient  in  different  classes  of  ships  it  may  be  noted  that, 
roughly,  these  are: 

Slow  cargo  vessels 80 

Ordinary  cargo  vessels 75 

Sailing  vessels 70 

Older  battleships 65 

Later  battleships 60 

Mail  and  passenger  steamers 60 

Cruisers 55 

Fast  cruisers 50 

Destroyers 45 

Steam  yachts 40 

2.  GENERAL  ARRANGEMENT 

The  lines  of  a  ship  determine  her  geometrical  form  or 
molded  surface.  The  ship  is  actually  built  by  providing  a 
certain  frame  work,  all  the  outer  points  of  which  lie  in  this 
molded  surface.  Over  this  frame  work  and  attached  to 
it  is  then  fitted  a  complete  envelope  of  plating  or  planking 
which  forms  the  "skin"  of  the  ship,  keeps  out  the  water, 
and  assists  in  furnishing  strength.  The  inner  surface  of 
the  plating  or  planking  therefore  coincides  with  the  outer 
surface  of  the  frames,  or  molded  surface. 

The  framing  is,  of  course,  the  important  part  of  the  ship 
and  furnishes  the  necessary  structural  strength.  Using 


42  PRACTICAL  SHIP  PRODUCTION 

the  term,  in  a  general  sense,  the  framing  may  be  said  to 
consist  of  all  the  principal  members  of  the  ship  except  the 
shell.  The  framing  and  shell  with  their  various  connections 
are  collectively  known  as  the  hull  of  the  ship. 

The  principal  parts  of  the  hull  of  every  ship  are  designed 
to  serve,  in  general,  the  same  purposes,  whether  the  ship 
be  wood,  iron,  steel,  concrete,  or  a  combination  of  any  or  all 
of  these.  It  will  therefore  be  sufficient,  in  discussing  these 
parts,  to  consider  only  the  modern  steel  ship,  which  repre- 
sents by  far  the  most  common  type  at  the  present  time. 
The  corresponding  members  of  ships  built  of  other  materials 
perform  similar  functions,  and  can  be  readily  compared  with 
those  of  the  steel  ship.  The  general  interior  arrangement 
of  a  typical  steel  cargo  carrying  steamer  is  shown  in  Fig. 
18,  which  represents  a  longitudinal  centre  line  section  of 
such  a  ship.  In  order  to  give  a  general  idea  of  the  interior 
arrangement  of  all  ships  the  various  subdivisions,  parts 
and  fittings  of  this  ship  will  be  briefly  described. 

Running  longitudinally  along  the  centre  of  the  bottom 
is  the  keel,  which  is  connected  at  its  forward  end  to  the 
stem,  a  heavy  cast  or  forged  steel  bar  or  post  bent  to 
the  shape  shown  and  extending  nearly  vertically  to  the 
highest  point  of  the  bow.  At  its  after  end  the  keel  is  con- 
nected to  another  heavy  steel  member,  usually  a  casting, 
called  the  stern-post  or  stern-frame,  which  extends  up  to  the 
counter.  This  forms  the  after  end  of  the  ship,  and  to  it  is 
secured  the  stern  framing  and  the  after  plating  of  the  shell. 

The  shell  plating  is  supported  by  frames  distributed 
throughout  the  length  of  the  ship  at  regular  intervals  so  as 
to  give  it  sufficient  support.  At  the  bow  the  shell  plating 
is  attached  to  the  stem,  and  at  the  stern  to  the  stern  post. 
The  transverse  frames  are  given  support  against  fore  and 
aft  movement  by  longitudinal  framing  running  along  their 
inner  edges  so  that  the  framing  of  the  ship  really  consists 
of  a  net  work  of  fore  and  aft  and  transverse  members 
crossing  each  other  approximately  at  right  angles.  All 
of  this  framing  is  in  turn  further  supported  by  the  decks 
and  bulkheads,  which  are  described  below. 


GENERAL  DESCRIPTION  OF  SHIPS 


43 


Is.  !*  S  11 
IE  gg  !  « 


44  PRACTICAL  SHIP  PRODUCTION 

The  upper  portion  of  the  main  hull  is  closed  in  by  a  com- 
plete deck  which,  in  Fig.  18,  is  marked  shelter  deck.  This 
is  the  highest  complete  exposed  deck  and  is  often  spoken 
of  as  the  weather  deck.  As  it  is  usually  the  principal  strength 
deck,  it  is  often  also  called  the  main  deck.  Sometimes  it  is 
called  the  spar  deck,  a  term  derived  from  its  proximity  to 
the  masts  and  spars.  This  deck  consists  of  a  slightly 
curved  and  approximately  horizontal  surface  under  which 
are  fitted  heavy  steel  beams  to  the  top  of  which  is  fastened 
the  deck  plating. 

Below  the  shelter  deck  and  running  parallel  to  it  is 
another  deck  called  the  upper  deck,  and  below  that  and 
also  parallel  to  it  and  to  the  shelter  deck  is  the  second 
deck.  The  space  between  the  shelter  and  upper  decks  is 
called  the  upper  'tween  deck,  and  between  the  upper  and 
second  decks  the  lower  'tween  deck.  Decks  are  usually  fitted 
with  a  vertical  distance  between  adjacent  decks  of  from  six 
to  eight  feet.  They  are  given  various  names  depending 
upon  the  type  of  the  ship  in  which  fitted.  They  corre- 
spond to  the  floors  of  a  building  on  shore,  and  serve  to 
subdivide  the  space  in  the  ship  so  that  it  can  be  conveniently 
utilized.  They  also  contribute  to  the  strength  of  the  hull 
by  furnishing  a  certain  amount  of  both  longitudinal  and 
transverse  stiffness,  and  also  limit  the  amount  of  volume 
that  may  be  flooded  in  case  the  shell  plating  is  punctured. 
In  ordinary  sized  cargo  vessels  it  is  not  usual  to  find  more 
than  two  'tween  decks. 

The  volume  of  the  hull  is  further  subdivided  by  means  of 
transverse  and  longitudinal  bulkheads,  or  partitions,  which 
correspond  to  the  walls  of  a  building.  These  are  flat 
plated  surfaces  stiffened  by  means  of  vertical  bars  called 
bulkhead  stiff eners. 

The  transverse  bulkheads,  as  well  as  dividing  the  volume 
of  the  hull  up  into  separate  compartments,  serve  to  furnish 
transverse  strength  and  to  transmit  the  forces  set  up 
by  the  various  weights  carried  in  the  ship  to  the  lower 
portion  of  the  hull.  In  case  of  damage  to  the  shell  plating 
below  the  water  line,  they  serve  to  limit  the  amount  of 


GENERAL  DESCRIPTION  OF  SHIPS  45 

space  in  the  ship  that  may  be  flooded,  and  are  made  espe- 
cially strong  for  this  purpose.  It  will  be  noted  in  Fig.  18 
that  the  transverse  bulkheads  separate  the  following 
compartments:  Fore  peak  tank,  No.  1  hold,  No.  2  hold, 
No.  3  hold,  coal  bunker,  boiler  room,  engine  room,  No.  4 
hold,  No.  5  hold,  and  after  peak  tank. 

Longitudinal  bulkheads  (which  are  not  indicated  in  the 
figure)  are  fitted  mainly  for  purposes  of  subdivision,  being 
limited  in  length  so  that  they  contribute  very  little  to  the 
longitudinal  strength  of  the  ship. 

The  forward  and  after  peak  tanks  are  large  compartments 
located  at  the  extreme  ends  of  the  ship  just  above  the 
bottom.  They  are  connected  by  suitable  piping  so  that 
they  can  be  readily  filled  or  emptied  of  water.  They 
can  thus  be  used  for  trimming  the  ship,  which  is  the  term 
applied  to  the  process  of  raising  or  lowering  one  end  or 
the  other  of  the  ship.  A  considerable  weight  of  water  can 
be  put  into  either  of  these  tanks,  which,  owing  to  its  location 
at  the  extreme  end  of  the  ship,  has  a  great  leverage  resulting 
in  deeper  immersion  of  that  end.  These  compartments 
are  also  sometimes  called  the  forward  and  after  trimming 
tanks.  The  bulkhead  at  the  after  end  of  the  fore  peak 
tank  is  sometimes  called  a  collision  bulkhead,  since  this 
bulkhead,  in  the  event  of  damage  caused  by  the  ship's 
running  into  another  ship  or  obstacle,  would  prevent 
water  from  entering  the  remainder  of  the  hull. 

The  holds  (Nos.  1,  2,  3,  4  and  5,  in  Fig.  18)  are  large 
spaces  used  for  carrying  cargo.  They  extend  completely 
across  the  ship  to  the  shell  plating  on  each  side  and  up  to  the 
second  deck. 

In  order  to  load  cargo  into  the  holds  and  'tween  deck 
spaces  there  are  provided  large  rectangular  openings 
in  the  decks  called  cargo  hatches.  The  edges  of  these 
openings  are  fitted  with  vertical  plate  boundaries  called 
coamings,  and  covers  are  provided  to  fit  in  these  coamings. 
After  a  hold  has  been  loaded  with  cargo  the  covers  are  put 
in  place  and  the  loading  of  the  'tween  deck  space  above  can 
be  proceeded  with. 


46  PRACTICAL  SHIP  PRODUCTION 

The  remainder  of  the  main  portion  of  the  space  in  the 
hull  is  devoted  to  the  requirements  of  propulsion,  there 
being  provided,  as  shown  in  Fig.  18,  an  engine  room, 
boiler  room,  and  coal  bunkers.  In  the  engine  room  are 
located  the  main  engines,  condensers,  pumps,  and  other 
auxiliary  machinery,  the  engines  being  connected  to  the 
propellers  at  the  stern  of  the  ship  by  longitudinal  shafts. 
These  shafts  pass  through  shaft  tunnels,  which  are  long 
water-tight  compartments  completely  closed  in  by  steel 
plating  so  as  to  be  entirely  independent  of  the  holds 
through  which  they  pass.  The  after  end  is  connected 
to  the  weather  deck  by  means  of  a  vertical  passage,  or 
trunk,  which  serves  both  as  a  ventilator  and  as  a  means 
for  escape  for  the  engine  room  force  in  case  of  emergency. 
A  large  vertical  inclosure,  or  trunk,  extends  from  the 
engine  room  up  to  the  weather  deck  where  it  terminates 
in  a  large  hatch  covered  by  a  skylight.  This  trunk  per- 
mits large  machinery  parts  to  be  removed  from  the  engine 
room  and  furnishes  light  and  ventilation. 

The  boiler  room  is  located  just  forward  of  the  engine 
room  and,  like  the  latter,  is  continued  to  the  weather  deck 
in  the  form  of  an  enclosure  through  which  passes  the 
uptake,  a  large  duct  which  connects  the  boilers  to  the 
smokestack.  In  addition  to  the  boilers  this  compartment 
usually  contains  certain  pumps  and  auxiliaries. 

The  coal  bunkers  are  large  compartments  used  for  the 
stowage  of  sufficient  coal  for  the  longest  voyages  which 
it  is  designed  the  ship  shall  make.  They  are  fitted  with 
hatches  similar  to  the  cargo  hatches,  by  means  of  which 
the  coal  is  dumped  into  them.  It  will  be  noted  that 
No.  3  hold,  when  not  desired  for  cargo,  can  be  utilized  as  a 
coal  bunker.  Coal  bunkers  are  also  located  outboard 
abreast  the  engine  and  boiler  rooms,  on  both  sides,  being 
separated  from  them  by  longitudinal  bulkheads.  (These 
are  not  shown  in  Fig.  18.) 

The  amount  of  space  devoted  in  cargo  vessels  to  engines, 
boilers,  and  fuel  is  much  smaller  than  in  some  other  types 
of  ships,  since  cargo  vessels  usually  cruise  at  comparatively 


GENERAL  DESCRIPTION  OF  SHIPS  47 

low  speeds,  and  therefore  do  not  require  the  power  and 
do  not  have  the  high  fuel  consumption  that  is  necessary 
for  high-speed  vessels. 

The  holds  and  'tween  decks  are  usually  numbered  con- 
secutively from  forward  to  aft,  the  'tween  deck  numbers 
corresponding  to  the  holds  directly  underneath  them. 

The  ship  shown  in  Fig.  18  is  fitted  with  an  inner  bottom 
extending  for  the  full  length  between  the  fore  and  after 
peak  tanks:  This  inner  bottom  runs  approximately  parallel 
to  the  outer  bottom  at  a  distance  of  about  four  feet  above 
it,  extending  to  the  turn  of  the  bilge  on  each  side  where 
it  curves  down  and  joins  the  outer  bottom  thus  forming  a 
separate  double  bottom  to  the  ship.  This  double  bottom 
is  divided  up  into  a  number  of  double  bottom  tanks  by 
means  of  partitions  located  directly  underneath  the  trans- 
verse bulkheads,  as  shown.  These  tanks  are  used  for 
carrying  water  as  ballast  when  the  ship  is  light  or  without 
cargo,  and  some  of  them  for  reserve  feed  water  for  the 
boilers,  being  suitably  connected  with  piping  for  filling 
and  emptying.  The  inner  bottom,  which  forms  the  upper 
boundary  of  these  tanks,  is  often  called  the  tank  top. 
When  a  cargo  ship  has  no  cargo  on  board,  the  double 
bottom  tanks  must  be  filled  in  order  to  give  her  sufficient 
stability,  and  when  in  this  condition  she  is  said  to  be  in 
ballast. 

In  order  that  the  ship  may  be  anchored  when  it  is  not 
convenient  for  her  to  go  alongside  of  a  dock  she  is  provided 
with  two  or  more  anchors  shackled  to  the  ends  of  chain 
cables.  The  chain  cables  pass  from  the  anchors  through 
large  passages  through  the  bows  of  the  ship  called  hawse 
pipes  and  over  a  specially  shaped  drum  of  the  anchor 
windlass  and  down  through  chain  pipes  into  a  large  com- 
partment located  just  aft  of  the  fore  peak  tank  called  the 
chain  locker. 

The  steering  engine  which  actuates  the  tiller  is  located 
in  a  special  compartment  just  above  the  rudder  at  the 
extreme  after  end  of  the  shelter  deck,  called  the  steering 
engine  room. 


48  PRACTICAL  SHIP  PRODUCTION 

The  extreme  forward  and  after  portions  of  the  hull 
above  the  peak  tanks  are  utilized  for  storerooms  and  living 
spaces  for  the  crew  (called  crew's  quarters).  Quarters 
for  some  of  the  crew  are  also  provided  just  forward  of 
the  steering  engine  room  and  also  abreast  of  the  engine 
room  and  uptake  trunks  amidships  on  the  shelter  deck. 
The  galley  (kitchen)  and  crew's  mess  room  (dining  room) 
are  also  located  amidships  on  the  weather  deck,  as  shown, 
all  of  these  compartments  being  inclosed  in  a  deck  house 
formed  by  continuing  the  sides  of  the  ship  up  for  a  portion 
of  the  length  and  decking  over  the  top.  This  deck  is 
called  the  boat  deck,  since  it  is  utilized  for  the  stowage 
of  the  ship's  boats.  There  is  also  installed  on  the  boat 
deck  the  radio  room  which  contains  the  radio  instruments 
and  sleeping  accommodations  for  the  radio  operators. 

Just  aft  of  the  hatch  leading  to  No.  3  hold  is  a  structure 
extending  up  for  four  deck  levels,  which  consists  of  officers' 
staterooms  and  mess  room  on  two  levels,  with  the  captain's 
quarters  above  these,  and  the  bridge  and  chart  house  on 
top.  The  bridge  is  a  semi-enclosed  platform  extending 
all  the  way  across  the  ship  and  so  arranged  as  to  give  a 
good  view  all  around  the  horizon.  It  is  from  the  bridge 
that  the  ship  is  controlled  and  steered,  there  being  located 
there  the  steering  wheel,  compass,  and  various  connections 
to  the  engine  room  and  other  parts  of  the  ship.  The  chart 
house  is  a  small  house  located  just  off  the  bridge  for  use  in 
plotting  the  course  of  the  ship  on  the  chart  and  doing  other 
work  in  connection  with  navigation  which  must  be  done  in 
a  sheltered  position.  The  captain's  quarters  are  directly 
under  the  bridge  in  order  that  he  may  have  access  thereto 
with  the  least  possible  delay  in  case  of  an  emergency. 

Two  masts  are  installed  as  shown  (the  foremast  and 
mainmast),  these  serving  as  supports  for  the  aerial  of  the 
radio  apparatus,  for  use  in  hoisting  signals,  to  provide 
stations  high  above  the  water  for  lookouts,  and  as  a  support 
for  the  booms  used  in  loading  and  unloading  cargo.  These 
masts  could  also  be  used,  in  case  the  machinery  should 
break  down,  to  spread  sails.  Special  derrick  posts  are 


GENERAL  DESCRIPTION  OF  SHIPS  49 

also  installed,  as  shown,  for  cargo  booms  serving  hatches 
not  located  convenient  to  masts.  Steam  winches  are 
located  at  various  points  on  the  weather  deck  for  furnishing 
power  for  the  gear  of  the  cargo  booms  and  other  hoisting 
arrangements. 

Air  is  supplied  to  the  various  compartments  of  the  ship 
by  means  of  special  ventilating  ducts  fitted  at  their  upper 
ends  with  hoods  or  cowls  and  extending  down  to  the  com- 
partments to  which  they  are  to  supply  air.  As  has  been 
noted,  the  after  ventilating  trunk  serves  also  as  an  escape 
hatch  from  the  shaft  tunnel. 

The  foregoing  brief  description  will  serve  to  give  a  general 
idea  of  the  subdivision  and  arrangement  of  the  various 
spaces  of  this  particular  type  of  ship.  There  is,  however, 
considerable  latitude  in  the  arrangement  of  different  types 
of  ships  which  varies  with  the  purposes  for  which  designed. 
For  example,  the  amount  of  space  necessary  for  engines 
and  boilers  in  a  vessel  designed  to  make  25  knots  speed 
would  be  a  very  appreciable  proportion  of  her  total  volume, 
whereas  in  a  slow  tramp  steamer  it  is  relatively  small. 
In  war  ships,  with  their  special  requirements  of  guns, 
torpedoes,  magazines,  armor,  etc.,  the  interior  of  the  hull 
is  much  more  cut  up  than  that  of  the  ship  shown  in  Fig. 
18.  All  war  ships  are  much  more  minutely  subdivided  in 
order  to  limit  the  damage  which  may  be  caused  by  shell 
fire  or  torpedo  or  mine  explosions.  Much  of  the  space 
used  for  cargo  in  Fig.  18,  would  in  the  case  of  a  passenger 
vessel  be  utilized  for  state  rooms,  dining  saloons,  lounges, 
and  other  conveniences  for  the  passengers.  Vessels  de- 
signed for  carrying  fuel  oil,  gasoline,  molasses,  or  other 
fluids  in  bulk  have  the  holds  replaced  by  large  tanks, 
extending  to  the  weather  deck  and  terminated  by  expansion 
trunks  to  permit  of  changes  in  volume  due  to  variation  in 
temperature. 

Many  of  the  features  illustrated  in  Fig.  18  are,  how- 
ever, common  to  practically  all  large  modern  steel  ships. 
These  include  the  double  bottom,  peak  tanks,  bulkheads, 
decks,  steering  gear,  anchor  gear,  masts,  ventilation, 


50  PRACTICAL  SHIP  PRODUCTION 

bridge,  engine  and  boiler  rooms,  shaft  tunnels,  and  numer- 
ous other  parts.  The  interior  arrangement  of  any  ship  must 
be  governed  both  by  considerations  of  convenience  (as 
in  the  case  of  a  building  on  shore)  and  by  requirements 
of  buoyancy  and  stability,  which  make  it  necessary  to 
have  the  weights  of  the  ship  so  located  as  to  fulfil  the 
conditions  that  have  been  discussed  in  Chapter  I. 

3.  TYPES  OF  SHIPS 

Ships  may  be  classified  in  several  different  ways,  such 
as  with  reference  to  the  material  of  which  constructed, 
the  purpose  for  which  used,  the  speed,  etc. 

1.  Ships  Classified  with  Reference  to  Materials  of 
Hulls: 

(a)  Wood. 
(6)  Composite. 

(c)  Iron. 

(d)  Sheathed 

(e)  Steel  (bronze,  etc.). 
(/)    Concrete. 

(a)  Wooden  Ships. — The  first  ships  of  importance  were 
constructed  almost  entirely  of  wood,  which  formed  the 
keels,  keelsons,  stringers,  knees,  beams,  planking,  floor- 
ing, ceiling,  etc.  For  many  years  practically  all  ships 
were  built  of  wood,  and  it  was  not  until  well  into  the 
nineteenth  century  that  iron  appeared  as  a  shipbuilding 
material.  The  building  of  wooden  ships  thus  became 
more  or  less  of  an  art,  and  all  skilled  shipbuilders  were 
spoken  of  as  shipwrights,  a  term  meaning  literally  "  builders 
of  ships,"  but  now  applied  only  to  the  workmen  who  fit 
and  install  the  wood  decks  and  other  wooden  parts  form- 
ing integral  portions  of  the  hulls.  These  wooden  ships 
were  monuments  to  the  shipwright's  skill,  and  performed 
excellent  service  for  many  years,  but  as  the  demand  for 
increase  in  size  appeared,  and  with  the  introduction  of 
the  use  of  iron,  it  was  gradually  found  advisable  almost 
entirely  to  abandon  the  use  of  wood  for  hull  construction. 


GENERAL  DESCRIPTION  OF  SHIPS  51 

The  reason  for  this  is  that  it  is  very  difficult  to  fasten  the 
various  parts  of  a  wooden  ship  together  so  as  to  prevent  a 
certain  amount  of  slipping  or  sliding  of  each  part  on  its 
neighbor.  These  strains  becoming  accumulative,  in  a 
large  ship,  would  cause  such  a  great  total  distortion  as 
to  make  the  use  of  wood  for  ships  of  such  size  practically 
prohibitive.  Very  few  wooden  ships  have  ever  been  built 
to  lengths  of  over  300  feet,  while  the  most  successful  ones 
have  been  little  over  200  feet  long.  When  it  is  remembered 
that  ships  are  now  built  with  lengths  approximating  1000 
feet,  the  limitations  of  wooden  ships  are  readily  seen. 
Nevertheless,  for  small  vessels  designed  to  operate  along 
the  coast  or  in  protected  waters  wood  is  a  very  satis- 
factory material  owing  to  its  cheapness  and  the  ease  with 
which  it  can  be  worked. 

(b)  Composite  Ships. — The  difficulties  mentioned  in  con- 
nection with  wooden  ships  can  be  considerably  overcome 
by  introducing  a  certain  amount  of  metal  into  the  con- 
struction.    In   fact,    modern   wooden   ships   of   any    size 
usually    have    certain    steel    strappings    and    reinforcing 
members.     When  the  entire  framing  of  a  ship  is  built  of 
iron,  steel,  or  other  metal,  but  the  outer  skin  is  still  of 
wood  planking,  she  is  known  as  a  composite  ship.     Such 
vessels  have  the  advantage  of  not  requiring  dry- docking 
for  purposes  of  cleaning  the  bottom  so  frequently. 

(c)  Iron  Ships. — Iron  came  into  general  use  for  ships' 
hulls  during  the  latter  part  of  the  first  half  of  the  nineteenth 
century.     The   principles    of   iron   shipbuilding   were,    in 
general,  the  same  as  those  now  applied  to  steel,  the  sizes 
of  the  various  members,  however,  being  necessarily  greater 
for  iron  on  account  of  its  lower  strength.     Iron  is  prac- 
tically never  used,  however,  for  shipbuilding  at  the  present 
time  except  for  certain  forgings  and  for  rivets  for  some 
merchant  ships.     Iron  has  a  greater  resistance  to  corrosion 
than  steel,  and  it  is  not  unusual  to  find  old  iron  vessels, 
built  perhaps  half  a  century  ago,  still  in  an  excellent  state 
of  preservation. 


52  PRACTICAL  SHIP  PRODUCTION 

(d)  Sheathed   Ships. — In   order  to  protect  the  under 
water  hull  of  an  iron  or  steel  ship  from  fouling,  due  to 
various   marine   growths,   it   is   sometimes   customary   to 
sheathe  it  with  wood  over  the  iron  or  steel  plating  below 
the  water  line,  and  to  cover  the  wood  with  sheets  of  copper 
secured  to  the  wood  with  copper  nails.     This  necessitates 
the  use  of  bronze  for  the  stem,  stern  posts,  struts,  etc., 
in  order  to  prevent  galvanic  action,  and  great  care  must 
be  exercised  to  see  that  the  copper  on  the  outside  of  the 
wood  sheathing  is  thoroughly  insulated  from  the  steel 
or  iron  shell  plating  inside.     Sheathed  ships  are  stronger 
than  composite  ships  but  of  more  expensive  construction. 
They  are  used  principally  in  tropical  waters  where  marine 
growths  are  excessive,  in  order  to  avoid  frequent  dry- 
dockings.     (Dry-docking    consists   in   landing   the   vessel 
in  a  large  basin,  or  dry-dock,  from  which  the  water  can 
be  pumped  out  so  as  to  render  the  under  water  portion 
of  the  vessel  accessible  for  cleaning  and  repairs.) 

(e)  Steel  Ships. — The  steel  ship  is  the  type  most  com- 
monly built  at  the  present  time  and  has  so  many  advan- 
tages over  all  other  types  that  it  is  practically  universally 
recognized  as  the  modern  ship.     Wood  and  concrete  ship 
construction  have  recently  received  a  great  impetus,  but 
this  is  admitted  to  be  due  rather  to  the  suddenly  increased 
need  for  overseas  transportation,  which  renders  the  con- 
struction of  all  types  of  ships  advisable,  rather  than  to 
any    superiority    of   these    ships    over    steel    ships.     The 
principal  advantage  claimed  for  wood  and  concrete  ships 
at  the  present  time  is  that  their  construction  will  supple- 
ment rather  than  replace  steel  construction,  and  can  be 
carried  on  at  the  same  time  by  utilizing  other  materials 
and  a  different  class  of  labor.     It  is  practically  certain 
that  steel  ships  will  be  the  standard  for  many  years  to 
come  and  that  by  far  the  greatest  proportion  of  ships 
constructed   will   have   steel   hulls.     Recent    experiments 
indicate  that  a  great  improvement  may  be  made  in  the 
methods  of  steel  ship   construction  by  the  substitution 
of  electric  welding  as  a  means  for  fastening  the  various 


GENERAL  DESCRIPTION  OF  SHIPS  53 

parts  together  instead  of  riveting.  Yachts  and  small 
torpedo  vessels  are  sometimes  constructed  of  bronze 
instead  of  steel,  but  the  principles  of  construction  are 
practically  the  same  as  for  steel  vessels. 

(f)  Concrete  Ships. — Reinforced  concrete  has  been  con- 
sidered for  a  number  of  years  as  a  material  for  ships,  and  a 
number  of  small  craft,  barges,  etc.,  have  actually  been 
built  on  this  principle,  but  it  is  only  comparatively  re- 
cently that  large  vessels  designed  for  overseas  service 
have  been  built  of  reinforced  concrete.  However,  the 
recent  great  demand  for  ships  of  all  kinds  has  resulted  in  a 
great  deal  of  attention  being  paid  to  the  construction  of 
reinforced  concrete  vessels.  The  principal  obstacles  in 
the  way  of  building  ships  of  this  material  are  the  relatively 
great  weight  and  volume  of  the  material  required  to  obtain 
the  necessary  strength,  the  liability  of  the  material  to 
crack  when  subjected  to  stress  in  a  seaway,  and  the  dete- 
riorating effect  of  the  action  of  salt  water  on  the  concrete. 
It  is  claimed  by  the  advocates  of  concrete  ships  that  these 
obstacles  can  be  largely  overcome  and  that  they  are  more 
than  offset  by  the  advantages,  the  principal  ones  of  which 
are  cheapness  and  speed  of  production,  and  the  fact  that 
the  labor  required  for  their  construction  can  be  obtained 
without  drawing  on  the  supply  of  labor  necessary  for 
building  steel  ships. 

At  the  present  time  concrete  ships  must  still  be  con- 
sidered as  in  an  experimental  stage,  and  until  they  have 
been  built  in  sufficient  numbers  and  operated  satisfactorily 
for  continuous  and  extended  periods  of  time  to  demonstrate 
their  practicability,  the  advisability  of  laying  down  large 
numbers  of  such  vessels  is  open  to  some  question. 

2.  Ships  Classified  with  Reference  to  Purpose  for  Which 
Used.- 

(o)  WARSHIPS. 

(I)  Battleships. 

(II)  Cruisers. 

(III)  Gunboats. 

(IV)  Torpedo  craft. 


54  PRACTICAL  SHIP  PRODUCTION 

(V)  Mining  and  mine  sweeping  vessels. 
(VI)  Submarines. 
(VII)  Auxiliary  vessels. 

(6)  MERCHANT  SHIPS. 

(I)  Passenger  vessels. 

(II)  Cargo  vessels. 

(III)  Combined  passenger  and  cargo  vessels. 

(IV)  Tugs. 

(c)  SPECIAL  TYPES. 

(I)  Yachts,  house  boats,  etc. 
(II)  Salvage  and  wrecking  vessels. 

(III)  Dredges. 

(IV)  Fishing  vessels. 
(V)  Surveying  vessels. 

(VI)  Fire  and  water  boats. 

(And  numerous  other  miscellaneous  types.) 


(a)  Warships 

(I)  Battleships. — The  term  battleship  is  applied,  in 
general,  to  warships  designed  to  take  part  in  fleet  actions. 
It  is  a  more  or  less  elastic  term  sometimes  including  moni- 
tors and  small  coast  defense  ships,  and  some  vessels  that 
may  also  be  classified  as  cruisers.  The  modern  battle- 
ship represents  the  standard  type  of  warship,  from  which 
other  types  may  be  considered  as  developed.  It  is  the 
largest,  most  powerful  fighting  unit,  and  far  more  costly 
than  most  other  types  of  warships,  so  that  it  is  usual  to 
compare  the  strengths  of  the  various  navies  of  the  world 
in  terms  of  the  numbers  of  first-class  modern  battleships 
that  they  possess.  (" Battle  cruisers"  are  also  included 
in  this  classification.) 

Modern  battleships  are  often  called  "  super  dreadnoughts," 
being  developments  of  the  all-big-gun  type  of  ship  of 
which  the  British  " Dreadnought"  was  the  forerunner. 
They  are  characterized  by  great  size,  strong  offensive  and 
defensive  powers,  ability  to  keep  the  sea  in  all  kinds  of 
weather  for  prolonged  periods  of  time,  and  fairly  high 


GENERAL  DESCRIPTION  OF  SHIPS  55 

speeds.  They  are  especially  designed  for  great  strength 
and  safety  in  case  damaged  by  shell,  torpedo,  or  mine 
attack,  and  consequently  have  numerous  water-tight 
compartments,  armored  bulkheads,  decks,  and  special 
under  water  protection,  and  their  form  differs  consid- 
erably from  that  of  a  merchant  ship.  Great  beam  must 
be  provided  in  order  to  obtain  the  large  displacements 
required  and  the  necessary  stability.  The  displacements 
of  such  ships  range  between  30,000  and  40,000  tons.  The 
guns  carried  may  be  of  calibres  approximating  16" 
with  armor  of  corresponding  thickness.  Very  powerful 
engines  are  necessary  to  drive  these  great  ships  at  the 
required  speeds,  which  may  be  21  knots  or  greater. 

(II)  Cruisers. — Vessels  of  this  class  are  especially  char- 
acterized by  higher  speed  than  battleships.  They  natu- 
rally lack  in  protection  what  they  gain  in  speed  and  usu- 
ally have  a  much  smaller  armament  than  battleships.  They 
are  variously  subdivided  into  different  classes,  such  as 
battle  cruisers,  armored  cruisers,  protected  cruisers,  and  scout 
cruisers  or  scouts.  In  general,  the  purpose  of  cruisers  is 
to  serve  as  auxiliaries  to  the  main  battle  fleet,  doing  convoy 
and  scouting  duty,  protecting  commerce,  destroying  the 
enemy's  commerce,  engaging  enemy  cruisers,  etc.  Battle 
cruisers  are  high-speed  battleships  in  which  armor  and, 
in  some  cases,  armament  are  sacrificed  to  speed.  They 
may  have  speeds  ranging  between  25  and  30  knots.  In 
some  cases  they  have  guns  of  the  same  calibre  as  con- 
temporary battleships.  Owing  to  their  very  high  speed 
they  may  be  even  larger  and  longer  and  may  cost  more  to 
build  than  battleships.  Armored  cruisers  are  less  powerful 
and  less  speedy  than  battle  cruisers.  The  distinction  be- 
tween these  two  classes  is  not  exact  since  the  battle  cruiser 
is  a  comparatively  recent  type  and  may  be  correctly  called 
an  armored  cruiser,  whereas  the  old  armored  cruisers  are 
considerably  smaller  and  slower  than  battle  cruisers. 
Protected  cruisers  are  even  smaller  and  less  powerful  than 
armored  cruisers,  and  have  little  or  no  side  armor,  being 
provided  merely  with  a  protective  deck  near  the  water 


56  PRACTICAL  SHIP  PRODUCTION 

line.  They  are  designed  more  for  convoy  and  raiding 
service  and  should  not  take  a  direct  part  in  fleet  action. 
Scouts  are  light  high-speed  vessels  designed  primarily,  as 
their  name  implies,  for  scouting  service.  They  have  very 
little  protection,  moderate  armament,  good  seaworthiness, 
and  a  speed  in  the  neighborhood  of  35  knots.  The  general 
form  of  all  cruisers  resembles  that  of  battleships,  the 
lines,  however,  being  considerably  finer. 

(III)  Gunboats. — For  special  service  in  shallow  waters' 
along    coasts    or    in    rivers,    small   warship's    known    as 
gunboats   are   employed.     These   are   usually  'of   special 
design,  depending  upon  the  waters  in  which  they  are  to 
operate  and  may  be,  or  may  not  be,  protected  by  armor. 
They  usually  have   displacements   of  under   1000   tons. 
Often  they  are  converted  yachts. 

(IV)  Torpedo  Craft. — Formerly  small,  fast  vessels  were 
built  for  the  purpose  of  carrying  and  launching  torpedoes. 
These  were  called  torpedo  boats.     To  oppose  them  larger 
and  faster  vessels  were  built — along  similar  lines — called 
torpedo  boat  destroyers.     The  building  of  torpedo  boats, 
therefore,  was  gradually  abandoned,  the  duties  formerly 
performed  by  them  being  transferred  to  the  destroyers 
and    also    to    some    extent    to    submarines.     Destroyers 
have  been   gradually  enlarged  until  they  now  approach 
scouts  in  design  and  are  used  somewhat  for  the  same 
duty.     They  carry  both  guns  and  torpedoes  and  have   no 
armor,  and  are  given  very  high  speeds,  between  30  and 
40  knots.     Their  displacements  may  be  as  high  as  1000 
tons   or   even   more   than   this.     Their   principal   duties 
at  the  present  time  are  to  convoy  merchant  ships  and  to 
hunt  down  and  destroy  submarines. 

(V)  Mining  and  Mine-destroying  Vessels. — These  are 
specially  equipped  vessels  of  small  size  and  light    draft 
used  for  sowing  mines  and  for  sweeping  and  destroying  them. 

(VI)  Submarines. — Submarines   are    vessels   of   special 
construction  which  enables  them  either  to  run  on  the 
surface   of   the   sea   or   to   run   submerged.     Submerged 
running  is  accomplished  by  flooding  specially  constructed 


GENERAL  DESCRIPTION  OF  SHIPS  57 

tanks  so  as  to  destroy  all  except  a  very  small  amount  of 
the  buoyancy,  the  vessel  then  being  directed  downward 
below  the  surface  of  the  water  by  the  horizontal  thrust  of 
the  propellers  combined  with  the  action  of  horizontal 
rudders  or  hydroplanes.  The  hull  of  a  submarine  has, 
in  general,  a  cigar-shaped  form  and  a  circular  or  nearly 
circular  cross  section.  Propulsion  on  the  surface  is  usually 
accomplished  by  means  of  internal  combustion  engines, 
and  when  submerged,  by  means  of  storage  batteries  and 
electric  motors.  There  are  two  general  types  of  con- 
struction— the  single  hull  type  and  the  double  hull  type. 
Submarines  range  in  displacements  from  two  or  three  hun- 
dred tons  upward — some  very  large  "  submarine  cruisers" 
having  been  recently  constructed. 

(VII)  Auxiliary  Vessels. — In  order  to  supply  and  co- 
operate with  the  main  fleet  of  a  navy  certain  special  types 
of  ships  are  necessary.  Many  of  these  are  practically  the 
same  as  certain  types  of  merchant  ships  or  are  readily 
convertible  from  them.  These  include  transports,  hos- 
pital ships,  colliers,  oil  tankers,  ammunition  ships,  sup- 
ply ships,  repair  ships,  training  ships,  patrol  and  dispatch 
vessels,  tugs,  and  numerous  other  special  types. 

The  primary  purpose  of  all  warships  is  to  make  war 
and  they  are  all  designed  with  that  principal  object  in 
view,  so  that  questions  of  secondary  importance  to  that 
must  always  give  way  to  such  characteristics  as  offensive 
power,  safety  and  ability  to  continue  to  fight  even  when 
damaged  in  action,  ability  to  keep  the  sea  for  long  periods 
of  time,  etc.  For  these  reasons  they  must  be  designed  and 
constructed  with  much  more  care  than  merchant  vessels. 


(b)  Merchant  Ships 

(I)  Passenger  Vessels. — Passenger  vessels  usually  make 
voyages  on  a  schedule  between  the  same  terminal  ports. 
In  other  words,  they  run  on  the  same  lines  and  therefore 
they  are  usually  called  liners.  They  are  usually  of  large 
size  and  fairly  high  speed.  Almost  all  ships  that  carry 


58  PRACTICAL  SHIP  PRODUCTION 

passengers  carry  also  a  considerable  amount  of  cargo,  so 
that  the  number  of  strictly  passenger  vessels  is  very 
limited.  Examples  of  these  are  the  large  fast  vessels  of 
the  various  trans- Atlantic  lines.  Some  of  these  approxi- 
mate 1000  feet  in  length  and  have  gross  tonnages  of  50,000 
or  60,000  with  speeds  of  about  25  knots. 

(II)  Cargo  Vessels. — This   class   forms   the  largest   of 
all  vessels  afloat  and  handles  the  world's  commerce.     For 
reasons  of  economy  the  speed  of  cargo  vessels  is  usually 
between  eight  and  twelve  knots,  even  lower  speeds  being 
found  in  the  type  known  as  tramp  steamers.     The  main 
objects  sought  in  a  cargo  vessel  are  carrying  capacity  and 
economy  of  operation.     Consequently,  the  form  is  made 
very  full  and  the  amount  of  space  devoted  to  the  com- 
plement,  engines,  boilers,  fuel,  and  water  is  kept  as  low 
as  possible.     Such  vessels  are   often  parallel  sided  or  of 
uniform  cross  section  for  a  considerable  portion  of  their 
length.     The  main  portion  of  the  hull  is  taken  up  with 
cargo  spaces.     Some  cargo  ships  are  propelled  by  sails, 
sailing  ships  at  the  present   time  being,  in  fact,  practi- 
cally limited  to  cargo  carriers,  fishing  vessels  and  yachts. 
The  greater  number  of  cargo  vessels  are,  however,  propelled 
by  steam.     A  particular  class  of  cargo  vessels  are  those 
known  as  tankers,  which  are  designed  for  carrying  liquid 
cargoes   in   bulk.     They   are   usually  constructed  on  the 
longitudinal  or  Isherwood  system  of  framing. 

(III)  Combined  Passenger  and  Cargo  Vessels. — These 
comprise  vessels  having  the  characteristics  of  both  of  the 
two  preceding  classes,  the  amount  of  space  devoted  to 
passengers  and  cargo  varying  between  wide  limits.     The 
passengers  are  housed  in  the  spaces  on  the  upper  decks 
above   the   cargo.     Among  such  vessels   will   usually  be 
found  the  ships  of  the  various  coasting  lines.     The  speed 
of  these  ships  usually  ranges  between  10  and  20  knots  and 
their  tonnage  may  be  almost  any  figure  from  1000  up 
to  20,000  or  30,000  tons  gross,  the  design  varying  to  meet 
the  particular  needs  of  the  service  for  which  built. 


GENERAL  DESCRIPTION  OF  SHIPS  59 

(IV)  Tugs. — These  are  comparatively  small  vessels  used 
principally  in  harbors  and  along  the  coast  for  towing 
other  vessels  or  for  assisting  in  handling  them  about 
docks  and  wharves.  Seagoing  tugs  are  usually  from  150 
to  200  feet  long.  Harbor  tugs  are  considerably  smaller. 
They  are  given  comparatively  powerful  engines  and  must 
be  of  rugged  construction  with  propellers  designed  es- 
pecially for  towing. 

The  form  of  merchant  steamers  is,  in  general,  the  same 
in  all  cases,  the  lines  of  the  fast  ones  being,  of  course,  finer, 

Warship 


Merchant  Vessel 


Yacht 


FIG.  19. — Types  of  ships. 

but  'the  general  characteristics,  such  as  shape  of  stem 
and  stern,  rudders,  etc.,  being  nearly  always  the  same. 
Fig.  19  shows  the  general  form  of  the  profile  of  a  merchant 
ship,  as  compared  with  that  of  a  war  ship,  of  the  battle 
ship  or  cruiser  type,  and  a  yacht. 

(c)  Special  Types 

The  various  special  classes  of  vessels,  such  as  yachts, 
dredging,  wrecking,  and  fishing  vessels,  etc.,  are  too  numer- 
ous to  describe  in  detail.  Each  is  designed  to  fulfill  a 


60  PRACTICAL  SHIP  PRODUCTION 

special  purpose,  and  usually  varies  considerably  from  the 
others,  even  of  the  same  class. 

3.  Ships  Classified  with  Regard  to  Speed. — There  is  no 
exact  classification  of  ships  with  regard  to  speed,  but  it  is 
worth  noting  that  extremely  few  ships  have  a  speed  as 
high  as  35  knots,  and  that  speeds  as  low  as  6  or  7  knots 
are  often  found  in  the  case  of  tramp  steamers,  small  sail- 
ing ships,  vessels  towing,  etc.  A  rough  classification  with 
regard  to  speeds  is  given  below: 

Very  high  speed  (30-35  knots). 
Destroyers.] 
Scouts. 

Fast  (25-30  knots). 

Special  mail  and  passenger  steamers. 
Battle  cruisers. 

Moderately  high  speed  (20-25  knots). 
Battleships. 

Fast  passenger  steamers. 
Slow  cruisers. 

Good  speed  (15-20  knots). 
Passenger  steamers. 
Older  battleships. 
Very  fast  cargo  vessels. 
Steam  yachts. 

Fair  speed  (10-15  knots). 
Faster  cargo  vessels. 
Slower  passenger  vessels. 
Slower  steam  yachts. 
Seagoing  tugs  (not  towing). 

Slow  speed  (under  10  knots). 
Slow  cargo  vessels. 
Tramp  steamers. 
Sailing  vessels. 

(A  knot  is  a  speed  of  6080  feet  per  hour). 


GENERAL  DESCRIPTION  OF  SHIPS  61 

4.  TONNAGE  OF  SHIPS 

As  has  been  stated  in  Chapter  I,  the  weight  of  any  ship 
floating  in  water,  including  all  that  she  carries,  must  equal 
the  weight  of  the  water  that  she  displaces.  This  weight 
is  called  the  displacement  of  the  ship  and  is  usually  ex- 
pressed in  tons,  of  2240  Ibs.  each.  It  will  be  noted  that 
the  displacement  is  equal  to  the  weight  of  the  ship  plus 
all  that  she  carries,  so  that  the  displacement  of  any  ship 
is  variable  and  depends  upon  the  cargo  and  other  movable 
weights  that  she  has  on  board.  The  displacement  of  an 
ordinary  cargo  vessel,  for  example,  may  be  three  times  as 
much  when  she  is  fully  laden  as  when  she  is  light.  For 
this  reason  a  statement  of  the  displacement  of  a  cargo 
ship,  unless  the  condition  of  loading  is  included,  gives 
only  an  approximate  idea  of  her  size.  War  ships,  such  as 
battleships  and  cruisers,  a  large  percentage  of  the  weight 
of  which  is  fixed,  have  comparatively  little  variation  in 
displacement,  and  the  tonnage  of  such  ships  is  usually 
expressed  in  terms  of  their  normal  displacement. 

In  order  to  express  the  size  of  merchant  ships  it  is  usual 
to  refer  to  their  gross  and  net  tonnages.  These  are  both 
based  upon  certain  volumetric  measurements,  100  cu.  ft.  being 
reckoned  as  one  ton.  " Tonnage"  in  this  case,  then,  really 
means  volume.  The  gross  tonnage  is  a  measure  of  the 
internal  capacity  of  the  whole  ship.  The  net  tonnage 
is  obtained  by  deducting,  from  the  gross  tonnage,  allow- 
ances made  for  space  occupied  by  officers  and  crew  and 
their  effects,  navigation  space,  and  propelling  space. 
The  net  tonnage  is  thus  really  intended  to  be  a  measure 
of  the  passenger  and  cargo  carrying,  or  earning  power  of 
the  ship.  The  rules  for  making  these  measurements 
were  established  by  the  British  Board  of  Trade  and  have 
been  adopted  by  practically  all  civilized  countries. 

The  net  tonnage  is  always  less  than  the  gross  tonnage 
and  is  usually  about  63  per  cent,  of  it,  the  reasons  for  this 
being  that  the  rules  allow  a  deduction  of  32  per  cent,  for 
machinery  spaces  in  the  cases  of  ships  of  which  that  space 


62  PRACTICAL  SHIP  PRODUCTION 

is  between  13  and  20  per  cent,  of  the  gross  tonnage  and 
that  the  other  deductions  usually  amount  to  about  5  per 
cent.  The  great  majority  of  all  tonnage  usually  conies 
within  this  class. 

The  dead  weight  carrying  capacity  is  expressed  in  tons  of 
2240  Ibs.,  or  in  the  same  units  as  the  displacement.  It  is 
the  difference  between  the  displacement  of  the  ship  when 
light  and  when  fully  loaded  to  the  maximum  draft  allowed 
by  law.  In  other  words,  the  total  dead  weight  carrying 
capacity  of  any  ship  may  be  denned  as  the  weight,  in 
long  tons,  of  cargo,  fuel,  water,  stores,  officers,  crew, 
passengers  and  their  effects  that  can  be  safely  carried  by 
that  ship. 

There  are  therefore  at  least  four  different  tonnages  that 
may  be  applied  to  any  ship,  each  expressing  in  its  own  way 
the  size  and  therefore  the  usefulness  of  that  ship.  For 
ordinary  cargo  carrying  ships  the  full  load  displacement 
tonnage  is  about  1^  times  the  dead  weight  carrying 
capacity,  about  2K  times  the  gross  tonnage  and  about 
3%  times  the  net  tonnage.  The  dead  weight  carrying 
capacity  is  about  IK  times  the  gross  tonnage,  and  the 
net  tonnage  is  roughly  %  of  the  gross  tonnage. 

The  terms  gross  and  net  tonnage  and  dead  weight 
carrying  capacity  are  not  ordinarily  used  in  connection 
with  war  ships,  which  are  measured  in  terms  of  displace- 
ment. The  term  displacement  is  seldom  used  to  indicate 
the  size  of  a  merchant  ship  since  it  varies,  for  such  ships, 
through  a  wide  range.  Yachts  are  usually  measured 
in  the  same  manner  as  merchant  ships. 

For  purposes  of  insurance  there  have  been  established 
for  many  years  in  the  principal  maritime  countries  of  the 
world  certain  classification  societies,  all  of  which  publish 
ordinarily  each  year  a  Register  of  Shipping,  which  is  a 
large  book  containing  the  names  of  all  merchant  vessels 
of  the  world  together  with  their  size,  tonnage,  ownership, 
name  of  builder,  date  built,  and  other  data.  The  prin- 
cipal of  these  societies  is  Lloyds,  the  well-known  British 
society.  Another  British  society  is  known  as  the  British 


GENERAL  DESCRIPTION  OF  SHIPS  63 

Corporation.  In  France  is  the  Bureau  Veritas,  and  in  the 
United  States  the  American  Bureau  of  Shipping. 

These  Societies  issue  various  rules  under  which  they 
will  insure  ships,  and  they  therefore  have  a  very  pronounced 
influence  on  the  trend  of  ship  design  and  construction. 
Vessels  are  rated  by  these  various  societies  in  accordance 
with  their  design,  construction,  and  the  care  with  which 
they  have  been  kept  up,  each  ship  being  periodically 
inspected  by  the  surveyors  of  the  Society  and  the  rating 
modified,  if  necessary,  as  a  result  of  the  inspection. 

Merchant  vessels  are  also  classified  and  their  tonnage 
recorded  by  the  government  of  the  nation  of  which  they 
fly  the  flag.  The  methods  of  determining  the  tonnages 
for  this  purpose  are  practically  the  same  as  those  adopted 
by  the  various  classification  societies. 

6.  MATERIALS  USED  IN  SHIP  CONSTRUCTION 

The  principal  material,  which  is  in  almost  universal 
use  for  constructing  the  hulls  of  ships,  is  steel.  This  is 
found  in  the  form  of  forgings,  castings,  plates,  shapes,  and 
rivets.  Also  in  warships  certain  special  treatment  steel 
and  face  hardened  steel  for  armor  is  used.  Other  materials 
used,  though  nowhere  near  to  the  same  extent  as  steel, 
include  iron,  copper,  zinc,  lead,  tin,  bronze,  brass,  and 
other  compositions,  wood  of  all  kinds,  canvas,  cork,  asbestos, 
linoleum,  hemp  and  wire  rope,  cotton,  oakum,  rubber,  tar, 
paper,  glass,  leather,  various  tilings  and  deck  coverings, 
cements,  enamels  and  paints. 

Forgings. — Forgings  are  used  for  special  purposes  where 
great  strength  is  required.  Owing  to  the  irregular  shapes 
required  for  the  special  large  solid  parts  used  in  hull  con- 
struction, the  forging  of  which  is  more  or  less  complicated, 
and  because  of  the  fact  that  steel  castings  possessing  suffi- 
cient strength  for  most  purposes  can  now  be  obtained, 
there  are  very  few  large  forgings  used  in  the  hulls  of  ships. 
Forgings  are  used  principally  for  machinery  parts,  such  as 
crank  shafts,  propeller  shafts,  connecting  rods,  and  for 


64  PRACTICAL  SHIP  PRODUCTION 

rudder  stocks.  Occasionally  the  stem  and  stern  posts 
are  forgings.  Small  forgings  are  used  for  certain  hull 
fittings  and  working  parts. 

Castings. — Steel  castings  are  commonly  used  for  the 
stern  frame,  stem,  stern  tubes,  rudder  frame,  propeller 
struts,  machinery  bed  plates,  anchors,  hawse  pipes,  chain 
pipes,  pipe  flanges,  gun  mounts,  and  various  small  hull 
fittings.  Various  grades  of  steel  are  used  for  different 
ones  of  these  castings. 

Plates. — Plates  are  simply  rolled  sheets  of  steel  of  uni- 
form thickness.  They  range  in  thickness  from  about  J£" 
to  a  trifle  over  1".  Plates  less  than  J-£"  thick  are  generally 
spoken  of  as  sheets.  Very  thick  plates  are  used  in  war  ships 
for  protective  decks  and  for  armor  of  sides,  turrets,  bar- 
bettes, conning  towers,  etc.,  but  these  are  not  classed  as 
ordinary  ship  plates,  being  made  of  specially  treated  steel 
by  special  processes. 

Plates  are  used  for  the  shell,  inner  bottom,  bulkheads, 
decks,  trunks,  coamings  and  other  such  parts,  and  for 
various  floors,  brackets,  girders,  and  other  structural 
members. 

The  weight  of  a  cubic  foot  of  steel  is  approximately  490 
pounds,  so  that  a  plate  1"  thick  will  weigh  about  40.8 
pounds  per  square  foot.  Plates  are  commonly  specified 
by  weight  per  square  foot,  and  thus  a  "  twenty  pound 
plate"  means  one  slightly  less  than  Y^"  in  thickness.  (In 
the  case  of  wrought  iron,  which  weighs  480  pounds  per  cubic 
foot,  the  weight  of  a  plate,  per  inch  of  thickness,  is  almost 
exactly  40  pounds  per  square  foot.) 

Shapes. — Shapes  are  rolled  steel  bars  of  various  special 
constant  cross  sections.  The  shapes  most  commonly  used 
in  ship  construction  are  illustrated  in  Fig.  20.  They  are 
used  for  various  parts  of  the  ship's  framing  and  for  connect- 
ing different  plates  and  other  shapes. 

The  angle  bar  (/  bar},  which  is  shown  in  perspective 
in  the  upper  sketch  of  Fig.  20,  is  used  for  joining  two  other 
members  that  meet  at,  or  nearly  at,  right  angles.  The 
names  of  the  various  portions  of  the  angle  bar  are  indicated 


GENERAL  DESCRIPTION  OF  SHIPS 


65 


in  the  figure.  When  the  angle  made  by  the  two  legs  or 
flanges  is  not  90°  the  angle  bar  (or  angle,  as  it  is  often  called) 
is  said  to  be  beveled.  If  the  angle  is  greater  than  90° 
it  is  an  open  bevel,  and,  if  less,  a  closed  bevel.  The  same 
terms  apply  to  the  other  shapes  when  so  treated. 


Heel- 


-Toe 


ANGLE  BAR 
Bosom 


Web 


Upper  Flange 


CHANNEL 


Web 


jf  Flange 


BULB  ANGLE 


^Flange 


Web'" 


T-EAR 


T-BULB 


Bulb 


Flange 


Flange  "^ 


Z-BAR 


I-BEAM 


\ 


Flange 


FIG.  20.— Shipbuilding  shapes. 

Channels,  bulb  angles  and  Z-bars  are  developments  of 
the  simple  angle  bar,  as  shown.  They  are  used  in  cases 
where,  in  addition  to  connecting  other  members,  they  must 
also  furnish  more  stiffness  or  girder  strength  than  would 
be  given  by  simple  angles.  This  stiffness  is  supplied  by  the 


66  PRACTICAL  SHIP  PRODUCTION 

extra  " flange"  strength.  In  some  cases  sufficient  stiffness 
is  furnished  by  angles  with  unequal  legs  in  which  case  the 
shorter  leg  acts  as  one  flange  and  the  longer  leg  serves  as 
both  the  web  and  the  other  flange. 

The  I-beam  has  the  ideal  cross  section  for  girder  strength 
but  is  not  much  used  in  ship  construction  on  account  of 
the  difficulty  of  connecting  it  to  other  members. 

The  T-bar  and  T-bulb  resemble  somewhat  the  I-beam, 
and  can  be  more  conveniently  attached  to  other 
members. 

Shipbuilding  shapes  are  designated  by  the  dimensions 
of  their  legs  or  webs  and  flanges  and  their  weight  per 
linear  foot— for  example,  a  "3"  X  3"  X  6  Ib.  angle," 
a  "10"  X  3%"  X  3%"  X  21.8  Ib.  channel,"  etc.  These 
figures  are  called  scantlings.  These  dimensions  and  other 
characteristics  of  the  cross  sections  are  given  in  hand  books 
published  by  the  various  steel  companies.  They  differ 
slightly  for  shipbuilding  shapes  (which  are  rolled  specially) 
from  those  for  ordinary  structural  steel  as  used  for  bridges, 
buildings,  etc. 

In  addition  to  the  shapes  shown  in  Fig.  20  there  are  a 
few  others  used  occasionally  in  shipbuilding,  such  as  round, 
square,  and  flat  bars,  half  rounds  (solid  and  hollow),  etc. 

Rivets. — Rivets  are  small  malleable  metal  members  or 
fastenings,  used  to  connect  or  tie  together  the  various 
plates,  shapes,  forgings  and  castings  of  the  ship's  structure. 
A  rivet  consists  of  a  cylindrical  shank  or  body,  of  circular 
cross  section,  terminated  at  one  end  in  an  enlarged  portion 
or  head.  The  other  end  is  formed,  when  the  rivet  is  driven, 
into  a  point. 

Fig.  21  shows  a  rivet  before  being  driven,  and  also  the 
various  forms  of  rivet  heads  and  points  ordinarily  used  in 
shipbuilding. 

Rivets  are  usually  made  of  mild  steel,  although  in  some 
merchant  work  wrought  iron  rivets  are  used.  Where  high 
tensile  steel  plates  and  shapes  are  used  the  rivets  connecting 
them  are  also  made  of  high  tensile  steel.  For  connecting 


GENERAL  DESCRIPTION  OF  SHIPS 


67 


the  plates  and  shapes  of  bronze  vessels,  bronze  rivets 
are  used. 

A  rivet  is  designated  by  the  diameter  of  the  cylindrical 
portion,    or   shank,    before   being   driven.     The   ordinary 

sizes  are  M",  %",  H",  «",  H",  %",  1",  W  and  1^". 
Larger  sizes  are  rarely  needed,  and,  if  so,  are  ordered 
specially. 

HEADS 

^  i  ¥i 


Countersunk,    Countersunk,    Button, 
Raised  Flat       Con 


PAN-HEAD  RIVET 
BEFORE  BEING  DRIVEN 


Button,  Pan,  Pan, 

Straight  Neck  Coned  Neck   Straight  Neck 


RIVET  POINTS 


Snap 


Liverpool 


Countersunk.,         Countersunk., 
Full  Eaised 


Bearing  stress  here 


tress  due  to  couple  here 

Pan  Head 

Faying  surface 


Pull  in  pla^^^^Q^^^^^^^^^^^^^ 

k>vVV      TivXxOvS^vE ^ — ^ 

Shearing  stress  heW^ Hammered  Point 

DRIVEN  RIVET 
CONNECTING  TWO   PLATES 

FIG.  21. — Rivets. 

The  countersunk  head  rivet  shown  in  Fig.  21  is  used  in 
places  where  a  flat  or  flush  surface  is  required,  as  in  the 
riveting  of  the  shell  plating  to  a  bar  keel,  or  in  a  steel 
deck  to  be  covered  with  wood,  and  in  cases  where  the  head 
must  be  calked.  It  reduces  the  strength  of  the  plate,  how- 
ever, since  a  larger  portion  of  metal  is  cut  from  it.  Pan- 
head  rivets  are  used  wherever  it  is  possible.  Button-head 


68  PRACTICAL  SHIP  PRODUCTION 

rivets  are  used  for  appearance.  The  raised  countersunk 
head  gives  slightly  better  holding  qualities  than  the  flat 
head.  A  coned  neck  is  for  the  purpose  of  causing  the  rivet 
to  fill  completely  the  space  in  a  punched  hole,  which  is 
slightly  tapered. 

Countersunk  points,  like  countersunk  heads,  are  used 
where  a  flush  surface  is  required,  or  where  calking  the 
points  is  necessary.  The  best  example  of  this  is  in  the 
under  water  shell  plating  where  projections  would  increase 
the  resistance.  Button  points  are  used  for  purposes  of 
appearance.  Hammered  points  are  used  wherever  possible, 
being,  as  a  rule,  cheapest,  and  nearly  as  efficient  as  any 
other  points.  The  Liverpool  point  combines  some  of 
the  advantages  both  of  the  countersunk  and  of  the  ham- 
mered point.  The  full  or  raised  countersunk  point  is 
somewhat  stronger  than  if  perfectly  flush.  All  counter- 
sunk points  are,  in  practice,  somewhat  rounded  out,  or 
raised. 

The  lowest  sketch  of  Fig.  21  shows  a  rivet,  after  being 
driven,  connecting  two  plates  that  are  subjected  to  a  pull, 
as  shown  by  the  arrows.  This  pull  is  taken  by  the  rivet 
in  the  following  ways: 

(a)  There  is  a  tendency  for  the  body  or  shank  of  the  rivet 
to  be  crushed  by  the  bearing  pressure  on  its  upper  right, 
and  lower  left  sides.  (These  bearing  pressures  are  also 
taken  by  the  plates.) 

(&)  There  is  a  tendency  for  the  rivet  to  be  sheared  along 
the  plane  that  divides  the  two  plates  (the  faying  surface) . 

(c)  Owing  to  the  fact  that  the  pulls  in  the  two  plates 
do  not  act  in  exactly  the  same  straight  line  there  is  set 
up  a  couple,  tending  to  cause  the  head  of  the  rivet  to  move 
to  the  left,  and  the  point  to  move  to  the  right,  thus  bringing 
bearing  pressures,  acting  in  a  vertical  direction,  onto  the 
right  side  of  the  point  and  the  left  side  of  the  head,  which 
tend  to  tear  the  head  and  point  from  the  body  of  the  rivet. 
(These  pressures  also  tend  to  squeeze  in  the  plates  under 
the  edges  of  the  head  and  point.) 

In  all  steel  for  ship  construction  the  principal  important 


GENERAL  DESCRIPTION  OF  SHIPS  69 

qualities  required  are  strength,  toughness  and  elasticity. 
A  ship  differs  from  a  permanently  fixed  structure,  like  a 
building,  in  that  there  must  be  a  certain  amount  of  elastic 
flexibility  to  it.  This  is  due  to  the  forces  set  up  by  the 
motion  and  vibration  of  the  ship  when  under  way,  and  the 
action  of  the  waves  when  in  a  heavy  sea.  It  is  very  im- 
portant that  a  strict  uniformity  of  the  material  be  main- 
tained, and  all  ship  steel  should  be  carefully  manufactured, 
inspected,  and  tested  in  accordance  with  properly  drawn 
specifications. 

In  naval  vessels,  for  which  the  very  highest  quality  of 
material  is  essential,  the  steel  used  is  purchased  under 
very  strict  specifications  which  are  published  by  the  Navy 
Department.  Commercial  ship  steel  is  of  not  quite  so 
high  a  quality  but  is  considered  satisfactory  for  merchant 
ships.  Specifications  are  published  by  the  various  registra- 
tion societies  covering  steel  for  merchant  ships. 

The  shipbuilder  should  be  thoroughly  familiar  with  the 
various  physical  and  chemical  requirements  of  steel  that 
is  suitable  for  hull  construction.  Most  of  this  steel  is 
known  as  mild  steel,  and  is  made  by  the  open-hearth 
process.  It  usually  has  a  tensile  strength  of  about  60,000 
pounds  per  square  inch  and  a  shearing  strength  of  about 
50,000  pounds  per  square  inch.  For  special  strength 
combined  with  lightness  (as  in  destroyers,  scouts,  etc.) 
a  high  tensile^  steel  is  used  which  has  a  tensile  strength 
varying  between  75,000  and  95,000  pounds  per  square  inch. 
High  tensile  steel  is  about  K  stronger  than  mild  steel. 

Iron. — Cast  iron  is  used  for  certain  minor  parts  where 
strength  is  not  an  essential,  although  practically  never 
used  in  the  hull  proper.  Propeller  blades  of  merchant 
vessels  are  sometimes  made  of  cast  iron. 

Wrought  iron  is  used  for  anchor  chains,  anchors,  steering- 
gear  chains,  straps  for  blocks,  etc.,  miscellaneous  black- 
smith work,  piping,  etc.  It  should  have  a  tensile  strength 
of  about  45,000  pounds  per  square  inch  and  the  other 
physical  and  chemical  qualities  necessary  for  the  use  to 
which  put. 


70  PRACTICAL  SHIP  PRODUCTION 

Iron  does  not  corrode  as  rapidly  as  steel  but  has  much 
less  strength. 

Non-ferrous  Metals. — Zinc  is  used  principally  to  pre- 
sent rusting  or  corrosion  of  iron  or  steel  parts  due  to 
the  action  of  salt  water  in  contact  with  them.  For  this 
purpose  the  parts  may  be  completely  galvanized  or  small 
plates  of  rolled  zinc  may  be  attached  to  various  points 
of  the  underwater  hull  where  galvanic  action  is  especially 
apt  to  occur,  such  as  in  the  vicinity  of  propellers,  rudder, 
and  openings  in  the  shell  plating. 

Copper  is  used  for  certain  piping  systems  that  must 
stand  high  pressures,  for  various  kettles  and  steam  tables, 
in  sheets  for  sheathing  wood  planking  under  water  and 
combined  with  zinc  and  tin  in  various  bronzes  and  brasses 
used  for  castings. 

Manganese  bronze  is  used  principally  for  propeller  blades 
and  hubs.  It  has  a  very  high  tensile  strength,  about 
65,000  pounds  per  square  inch,  and  contains  approximately 
58  percent  of  copper,  40  percent  zinc  and  1  percent  manga- 
nese with  a  small  amount  of  tin,  aluminum,  iron  and  lead. 

Phosphor  bronze  is  used  for  stem,  stern,  and  rudder 
frames,  shaft  struts,  etc.,  of  bronze  or  sheathed  vessels.  It 
contains  about  90  percent  of  copper,  9J^  percent  of  tin  and 
^  percent  phosphorus,  and  has  a  tensile  strength  of  30,000 
to  35,000  pounds  per  square  inch. 

Naval  brass  contains  about  60  percent  copper,  37  percent 
zinc,  1  percent  tin,  with  a  small  amount  of  iron,  aluminum, 
and  lead.  There  is  less  tin  as  a  rule  in  brass  than  in  bronze. 
Brass  is  used  for  small  castings,  where  great  strength  is  not  so 
important,  being  much  weaker  than  bronze.  These  include 
rail  fittings,  scuppers,  stowage  brackets,  short  rail  and 
ladder  stanchions,  hatch  and  hatch  cover  frames,  skylight, 
door  and  scuttle  fittings,  pipe  flanges,  valves,  hand  wheels, 
air  port  fittings,  etc. 

The  percentages  of  the  materials  used  in  the  different 
copper-zinc-tin  alloys  vary  considerably,  slight  changes  in 
the  quantities  of  each  producing  entirely  different  qualities, 
to  suit  different  requirements. 


GENERAL  DESCRIPTION  OF  SHIPS  71 

Lead  is  used  for  lining  steel  and  copper  pipe,  sheathing 
in  cold  storage  spaces,  plumbing  work,  storage  battery 
tanks,  etc. 

Wood. — Nearly  all  kinds  of  wood  find  a  certain  use  in 
ship  construction.  Oak  and  yellow  pine  are  largely  used 
for  the  hulls  of  wooden  ships,  barges,  lighters,  tugs,  etc. 
In  steel  ships  wood  is  used  for  deck  planking,  partition 
bulkheads,  sheathing  in  coal  bunkers,  holds,  etc.,  for  masts, 
spars,  derricks,  gun-  and  small  machinery  foundations, 
ladders,  gangways,  hatch  covers,  gratings,  boats,  booms, 
furniture,  shelving,  lockers,  chests,  fittings,  and  for  a 
variety  of  other  minor  purposes.  For  auxiliary  purposes, 
during  the  building  of  the  hull  prior  to  launching,  wood  is 
used  to  a  considerable  extent  (piles,  cross  logs,  building 
blocks,  launching  ways,  staging,  scaffolding,  shoring, 
wedges,  etc.). 

Yellow  pine  is  most  used  for  decks,  although  teak  is 
somewhat  used  for  this  purpose.  Booms  and  spars  are 
commonly  made  of  pitch  pine,  Oregon  pine,  or  spruce, 
Sheathing  may  be  of  white  or  yellow  pine  depending  upon 
its  location  and  the  amount  of  wear  and  tear  to  which 
subjected.  A  considerable  variety  of  woods  are  in  use  for 
furniture,  stateroom  bulkheads,  lockers,  etc.,  etc.  Lignum 
vitse  is  used  for  stern  tube  bushings.  Blocking,  shoring 
and  wedges  are  commonly  of  yellow  pine  or  oak.  Piles 
are  usually  pine  or  fir  stems. 

Only  the  best  quality  of  timber  should  be  used  for  ship 
work  and  it  should  be  carefully  inspected.  The  most 
common  defects  to  be  looked  out  for  in  lumber  are  knots, 
shakes,  heart  centres,  worm  and  bee  holes,  crooked  grain, 
sap  wood,  splits,  wane,  extreme  curvature,  etc. 

Shakes  are  fissures  or  cracks  in  the  wood.  The  heart  is 
the  portion  of  the  wood  at  the  centre  of  the  trunk  of  the 
tree,  and  the  sap  wood  is  that  nearest  the  bark.  Wane 
is  an  inequality  in  a  board  or  plank  caused  by  its  being 
sawed  from  a  portion  of  the  log  too  close  to  the  outside. 

Flitches  are  slabs  or  pieces  of  timber  sawed  from  the  outer 
part  of  the  log.  Knees  are  pieces  of  timber  cut  from  the 


72  PRACTICAL  SHIP  PRODUCTION 

part  of  the  tree  where  the  roots  join  the  trunk,  so  that  they 
have  a  natural  curvature,  or  bend. 

Miscellaneous  Materials. — Canvas  is  used  for  awnings, 
sails,  tarpaulins,  hatch  hoods,  wind-sails  and  sometimes  as  a 
covering  over  wood  decks,  and  for  gaskets  and  stop-waters. 
Cork  is  used  for  sheathing  compartments  against  heat,  for 
life  preservers,  etc.  Asbestos  is  used  for  lagging  or  covering 
certain  pipes  or  bulkheads  subjected  to  high  temperatures. 
Linoleum  is  used  as  a  deck  covering.  Rope  is  used  for 
tackles,  purchases,  shrouds,  stays,  lifts  and  other  rigging 
parts.  Cotton  and  oakum  are  used  for  making  tight  the 
seams  between  deck  planks  and  outer  planking  of  sheathed 
or  wooden  vessels.  Rubber  is  used  extensively  for  gaskets 
of  water-tight  doors,  hatches,  manholes,  ports,  etc.  Tar 
and  leather  are  used  for  various  purposes  in  connection  with 
the  rigging.  Heavy  paper  or  cardboard  is  used  for  making 
templates  and  in  some  cases  for  gaskets  and  sto^-waters. 
Tarred  paper  is  used  in  insulating  bulkheads.  Ceramic 
tiling  and  various  special  compositions  are  used  as  deck 
coverings  in  bath  rooms,  wash  rooms,  galleys,  etc. 

Paints  and  Cements. — One  of  the  principal  drawbacks  to 
the  use  of  steel  for  ships  is  the  gradual  wasting  away  of  the 
material  caused  by  rust  or  corrosion.  In  order  to  prevent 
or  minimize  this  action  a  great  variety  of  paints  and  other 
protective  coatings  are  in  more  or  less  general  use.  The 
steel  bottoms  of  ships  must  also  be  coated  so  as  to  reduce,  as 
much  as  possible,  fouling,  or  the  attachment  to  the  plating 
of  various  marine  growths,  such  as  weeds,  grass,  shells, 
barnacles,  etc. 

Ship's  Bottom  Paints. — The  underwater  plating  of  steel 
ships  is  painted  with  anti-corrosive  and  anti-fouling  paints. 
The  anti-corrosive  paint  is  applied  usually  as  the  first  two 
coats,  to  the  underwater  plating  of  the  hull  and  is  for  the 
purpose  of  preventing  corrosion  or  rusting.  The  anti- 
fouling  paint  is  applied  over  the  anti-corrosive  (usually  as 
one  coat)  and  is  for  the  purpose  of  preventing  fouling,  or 
the  attachment  of  various  marine  growths.  In  order  to  do 
this  two  objects  are  sought:  (1)  to  make  the  paint  poison- 


GENERAL  DESCRIPTION  OF  SHIPS  73 

ous  so  as  to  kill  or  drive  off  the  seaweed,  barnacles,  etc.,  and 
(2)  to  give  it  a  certain  soapiness  so  that  by  gradually 
washing  away  it  will  continue  to  give  off  the  poison.  A 
great  many  different  special  ship's  bottom  paints  are  on  the 
market — some  good  and  some  poor.  None  is  entirely 
successful  in  attaining  the  objects  sought.  Anti-corrosive 
paints  were  formerly  almost  always  oil  paints,  plain  red 
lead  being  largely  used,  but  certain  quick  drying  paints  are 
now  used  considerably,  these  being  composed  of  alcohol, 
shellac,  zinc  oxide  and  other  similar  materials.  Such  paints 
do  not,  however,  adhere  well  to  bare  steel,  and  a  new 
ship  should  be  first  painted  with  red  lead,  which  fills  up  the 
pores  of  the  metal  and  when  scraped  off  gives  a  good  surface 
for  the  adherence  of  the  first  coat  of  anti-corrosive.  Anti- 
fouling  paints  are  given  their  poison  quality  by  the  use  of 
copper,  arsenic,  etc.  A  typical  paint  of  this  sort  contains 
alcohol,  shellac,  pine  tar,  turpentine,  white  zinc  oxide, 
Indian  red,  and  red  oxide  of  mercury. 

Oil  Paints. — For  ordinary  steel  material  exposed  to  the 
weather  or  to  moisture  the  most  commonly  used  protective 
paint  is  red  lead  or  oxide  of  lead  mixed  with  raw  linseed  oil 
and  a  small  quantity  of  petroleum  spirits  and  drier.  Other 
paints  may  contain  lead  carbonate,  iron  oxide,  metallic 
zinc,  zinc  oxide,  etc.  Red  lead  is  best,  however,  and  is 
used  to  a  very  great  extent.  It  is  used  as  a  first  coat  for 
practically  all  steel  material,  being  applied  to  the  dry, 
clean,  bare  metal.  Other  oil  paints  with  suitably  colored 
pigments  are  used  for  finishing  coats,  over  the  red  lead. 
The  vehicle  is  almost  always  linseed  oil. 

Bituminous  Compositions. — These  are  black  tar-like 
compositions  which  are  practically  impervious  to  water, 
and,  when  properly  applied,  adhere  well  to  steel.  They  are 
usually  in  the  form  of  a  solution,  an  enamel,  and  a  cement. 
They  are  sold  under  various  trade  names  and  the  manu- 
facturers keep  their  composition  more  or  less  secret.  How- 
ever, it  is  fairly  well  known  that  they  contain  various  kinds 
of  asphalt,  rosin,  Portland  cement,  slaked  lime,  petroleum, 
and  similar  ingredients.  The  solution  is  a  liquid  which  is 


74  PRACTICAL  SHIP  PRODUCTION 

applied  cold  with  a  brush  and  is  used  as  a  priming  coat  for 
either  the  enamel  or  cement.  The  enamel  is  applied  hot 
over  the  solution  after  the  latter  is  nearly  dry  or  set,  being 
poured  where  possible  and  otherwise  spread  over  the 
surfaces.  It  forms  a  tacky,  sticky  mass,  which  hardens 
as  it  cools,  but  always  remains  fairly  elastic  and  ductile. 
The  cement  is  also  applied  hot,  but  is  more  difficult  to 
apply  than  the  enamel  and  can  usually  be  applied  only  to 
horizontal  surfaces. 

Experience  with  such  compositions  has  not  always  been 
satisfactory.  It  has  been  noted  that  they  were  too  thin 
a  coating  to  give  proper  protection  against  coal  and  other 
hard  lumps  rubbing  against  them,  that  they  are  either  too 
brittle  and  flake  and  chip  off,  or  that  they  are  too  soft 
and  flow  at  only  moderately  high  temperatures,  and  that 
they  blister. 

Practically  all  of  these  objections  can,  however,  be,  and 
are  removed  by  proper  care  in  preparing  the  materials,  and 
intelligent  skill  in  their  application,  with  the  result  that  a 
highly  efficient  protective  coating  can  be  thus  obtained. 
Bituminous  solution  and  enamel  or  cement  are  therefore 
used  considerably  for  the  following  spaces  in  ships:  ballast 
and  trimming  tanks,  double  bottom  tanks,  chain  lockers, 
reserve  feed  tanks,  fresh  water  tanks,  tank  top,  coal  bunkers, 
engine  and  boiler  foundations,  etc.,  below  floor  plates, 
shaft  alleys,  and  various  spaces  that  are  not  readily  acces- 
sible for  cleaning  and  painting. 

In  applying  these  compositions  great  care  must  be  used 
to  see  that  the  metal  is  dry,  bare  and  absolutely  free  from 
rust,  dirt,  grease,  etc.,  and  that  wide  variations  in  the 
temperature  of  the  metal  are  avoided.  Cold  weather 
and  conditions  liable  to  cause  sweating  should  be  avoided. 
Artificial  ventilation  must  be  provided  for  the  workman, 
who,  even  then  can  work  in  the  fumes  for  only  short  periods 
at  a  stretch.  The  success  or  failure  of  such  coatings  de- 
pends upon  whether  or  not  they  are  applied  properly  in 
the  beginning. 


GENERAL  DESCRIPTION  OF  SHIPS  75 

Portland  Cement. — Portland  cement  of  good  quality, 
mixed  with  sand  (usually  about  2  or  2K  parts  of  sand  to 
1  part  of  cement)  is  used  in  ships  to  protect  the  steel 
material  where  it  is  subject  to  rubbing  of  various  hard 
articles,  where  it  is  not  readily  accessible  for  painting, 
where  also  necessary  for  drainage  purposes,  and  under 
tiling.  Where  the  thickness  must  be  considerable,  as  in 
the  pockets  between  frames  near  the  ends  of  the  ship, 
it  may  be  lightened  by  having  coke  mixed  with  it.  It  is 
not,  ordinarily,  used  in  double  bottoms.  If  the  cement 
does  not  adhere  firmly  to  the  metal  underneath  not  only 
will  corrosion  not  be  prevented,  but  it  may  go  undetected, 
which  is  serious.  For  this  reason  many  persons  are 
opposed  to  the  use  of  cement.  It  is  also  liable  to  be  cracked 
or  crumbled  by  the  action  of  the  vessel  in  a  seaway.  On 
the  other  hand,  if  properly  applied  it  should  form  a  good 
bond  with  the  steel,  and  has  several  advantages  over 
coatings  that  would  otherwise  be  used.  The  tendency, 
however,  seems  to  be  to  use  more  bituminous  compositions 
and  less  Portland  cement. 

Smoke  stack  paints  are  designed  to  withstand  the  heat 
to  which  they  are  normally  subjected.  They  contain 
litharge,  whiting,  lampblack,  silica,  white  lead,  white  zinc, 
mineral  oil,  etc. 

Shellacs,  varnishes  and  various  other  special  paints  are 
used  for  a  number  of  miscellaneous  purposes  on  board  ship. 

The  relative  advantages  of  various  paints,  compositions, 
cements,  varnishes,  etc.,  are  always  open  to  argument, 
since  none  are  perfect,  all  are  more  or  less  advertised,  and 
results  of  experience,  depending,  as  they  do,  upon  both 
material  and  skill  of  application,  are  not  always  reliable 
guides. 

A  knowledge  of  the  values  of  these  different  coatings 
as  preventers  of  corrosion  is,  however,  important  to  the 
shipbuilder,  and  even  more  so  to  the  ship  operator,  since 
if  corrosion  is  not  properly  prevented  the  ship  will  in  a 
few  years  be  wasted  away  to  nothing.  Good  paints  and 
other  coatings,  well  applied,  are  economies  in  the  long  run. 


76  PRACTICAL  SHIP  PRODUCTION 

Weights  of  Various  Materials. — It  is  necessary  fre- 
quently to  calculate  or  to  estimate  the  weights  of  various 
members,  parts  or  fittings  of  ships,  and  for  that  purpose 
the  unit  weights  of  some  of  the  materials  most  commonly 
used  should  be  known.  These  are  given  below: 

Weight  in  Ibs. 
Material  per  cu.  ft. 

Ship  steel 490 

Wrought  iron 480 

Cast  iron , 450 

Copper 550 

Brass  (about) 525 

Bronze 535-550 

Lead 710 

Live  oak 67 

White  oak  (about) 45 

White  pine;  spruce  (about) 30 

Teak 45-60 

Portland  cement  and  sand  (about) 130 

Cork  (about) 14 

Yellow  pine  (about) 45 


CHAPTER  III 

STRUCTURAL  MEMBERS  OF  SHIPS 
1.  TRANSVERSE  AND  LONGITUDINAL  FRAMING 

In  the  great  majority  of  ships  the  framing  is  of  the 
transverse  type — the  frames  forming  the  "ribs"  which 
extend  out  on  each  side  perpendicular  to  the  keel  or  "back 
bone."  This  principle  of  construction  is  simply  an  exten- 
sion of  that  shown  in  Fig.  13  (B).  The  keel  running  longi- 
tudinally along  the  centre  line  of  the  bottom  gives  fore  and 
aft  strength.  Considering  the  ship  as  a  girder  the  keel  forms 
a  portion  of  the  lower  "flange,"  the  main  deck  similarly 
forming  a  portion  of  the  upper  "flange." 


Shell  plating 


In  wooden  ships  the  keel  is  a  heavy  solid  timber  of 
rectangular  cross  section,  and  with  the  introduction  of  the 
use  of  iron  for  shipbuilding  purposes  it  was  naturally 
replaced  by  a  heavy  wrought  iron  bar  of  somewhat  similar 
cross  section.  Such  keels  are  still  used  to  some  extent  in 
steel  ships  and  are  called  bar  keels.  In  the  left-hand  sketch 
of  Fig.  22  is  shown  such  a  keel.  The  lower  plates  of  the 
shell  plating  are  flanged  or  bent  down  as  shown  so  as  to  fit 
snugly  against  the  sides  of  the  keel  to  which  they  are 

77 


78  PRACTICAL  SHIP  PRODUCTION 

fastened  by  means  of  long  through  rivets  extending  through 
the  three  thicknesses  of  plate,  keel,  and  plate.  Such  a  keel, 
owing  to  its  large  cross  section,  furnishes  considerable 
strength,  and,  owing  to  its  depth,  great  vertical  stiffness, 
but  it  has  the  disadvantage  of  increasing  the  draft  of  the 
ship,  and  it  has  therefore  been  replaced  in  almost  all  ships 
by  the  flat  plate  keel. 

The  right-hand  sketch  in  Fig.  22  shows  a  flat-plate  keel 
which  is  a  long  course  of  plating,  dished  on  each  side,  and 
connected  by  lap  joints  to  the  lower  plates  of  the  shell 
plating.  The  keel  therefore  forms  a  portion  of  the  shell 
plating.  In  this  type  of  construction  the  flat  plate  keel 
is  supplemented  by  a  continuous  vertical  plate,  as  shown 
in  the  figure,  called  the  centre  vertical  keel  or  centre  keelson. 
This  is  secured  to  the  flat  plate  keel  by  an  angle  bar  on  each 
side  and  is  stiffened  at  its  upper  edege  by  another  angle  bar 
on  each  side,  as  shown.  All  of  these  members  are  con- 
tinuous so  that  they  serve  to  form  a  deep  powerful  centre- 
line girder.  The  lower  flange  of  this  girder  is  further 
strengthened  by  the  shell  plating  attached  to  each  side  of 
the  keel. 

The  transverse  frames  furnish  the  direct  support  for  the 
shell  plating  against  the  pressure  of  the  water  and  also 
serve  to  transmit  the  vertical  forces  caused  by  the  wieghts 
carried  by  the  decks  down  to  the  bottom  of  the  ship.  On 
account  of  the  shape  of  the  ship  they  have  considerable 
curvature  and  constitute  one  of  the  features  of  steel  con- 
struction in  which  ships  differ  from  structures  of  other 
types. 

The  transverse  frames  are  located  at  stations  similar  to 
the  cross  sections  2,  3,  4,  5,  etc.,  in  Fig.  16,  but  are  spaced 
at  much  shorter  intervals.  The  interval  between  two 
successive  frames,  called  the  frame  spacing,  varies  between 
about  IS"  in  small  vessels  and  about  four  feet  in  large  ones. 
The  frame  spacing  is  normally  constant  throughout  the 
length  of  the  ship,  being  reduced  only  where  special  local 
stiffness  is  required  (as  under  engines,  boilers  and  other 
heavy  weights).  At  certain  of  the  frame  stations  the 


STRUCTURAL  MEMBERS  OF  SHIPS  79 

ordinary  frames  are  replaced  by  transverse  bulkheads, 
which  in  addition  to  serving  as  partitions,  may  be  con- 
sidered, in  this  connection,  as  solid  frames.  The  beams  of 
the  decks,  which  run  athwartships  between  the  upper 
portions  of  the  frames,  act  with  them  in  furnishing  trans- 
verse stiffness  and  complete  the  "ring"  of  each  frame. 

The  simplest  type  of  frame  is  a  single  angle  bar,  bent  to 
the  shape  of  the  section  at  which  it  is  located.  One  flange 
of  the  angle  bar  is  then  flat  and  lies  in  a  transverse  plane 
throughout  its  own  length,  the  heel  and  toe  of  this  flange 
being  curved  to  the  shape  of  the  transverse  section  of  the 
ship  at  that  frame  station.  The  line  of  the  heel  of  the  bar 
lies  in  the  molded  surface  of  the  ship,  and,  when  viewed 
from  directly  forward  or  aft,  has  the  exact  shape  of  the 
frame.  Due  to  the  form  of  the  ship  each  frame  curve  varies 
slightly  from  the  neighboring  ones  except  in  the  parallel 
middle  body. 

The  other,  or  longitudinal  flange  is  formed  to  and  lies  in 
the  molded  surface  of  the  ship,  so  that  the  inner  surface 
of  the  shell  plating  may  rest  snugly  against  it.  In  the 
parallel  middle  body  the  longitudinal  flange  is  everywhere 
at  right  angles  to  the  transverse  flange,  but  at  all  other 
parts  of  the  molded  surface  the  angles  between  the  flanges 
are  greater  than  90°,  on  account  of  the  transverse  curvature 
of  the  molded  surface.  This  is  due  to  the  fact  that  the 
frames  are  arranged  so  that  the  bosoms  of  those  in  the 
forward  portion  of  the  ship  will  "look"' aft,  and  of  those  in 
the  after  portion,  forward,  thus  giving  all  frames  an  open 
bevel. 

Figure  23  shows  a  portion  of  the  framing  and  shell  plating 
of  a  ship  fitted  with  simple  angle  frames.  The  planes 
ABC,  DEF,  and  GHK  are  planes  of  such  transverse  frames, 
being  drawn  square  to  the  keel  line  of  the  ship.  The 
distance  AD  or  DG  is  the  frame  spacing.  The  transverse 
flanges  of  the  frames  lie  in  these  transverse  planes,  as  shown, 
and  the  longitudinal  flanges  lie  in  the  molded  surface  or 
against  the  inner  surface  of  the  shell  plating.  The  con- 
struction is  shown  in  section  in  the  lower  portion  of  the 


PRACTICAL  SHIP  PRODUCTION 


figure,  the  necessary  bevel  of  the  frame  angle,  in  order  for 
it  to  fit  against  the  shell  plating,  being  as  indicated.  The 
shell  plating  is  fastened  to  the  longitudinal  flange  by  a  single 
row  of  rivets,  which  are  fairly  widely  spaced,  since  their 
spacing  has  no  effect  upon  the  water  tight  ness  of  the  shell. 


Shell  Plating 


Molded  Edge  or  Heel 
of  Frame  Angle 


Frames 


Longitudinal- 
Flange 


Angle  of  open  Bevel 


!K 


Transverse  Flange 
PERSPECTIVE  VIEW 


Molded  Edge 
/       |        /     of  Frame 


Shell  Plating 

Longitudinal  ' 
Flange  of  Frame 

'  SECTION   NORMAL 
TO  SHELL   PLATING 


^—Transverse  Plane 


FIG.  23. — Simple  transverse  framing. 

The  construction  just  described  might  be  suitable  for  a 
very  small  vessel,  but  for  larger  ones  it  does  not  give  suffi- 
cient stiffness,  and  therefore  it  is  customary  to  reinforce 
the  frame  angle  bar  by  another  angle  called  a  reverse  frame, 
or  to  substitute  for  the  simple  angle  frame  a  channel,  bulb 
angle,  or  Z-bar  as  shown  in  Fig.  24.  The  reverse  frame  is 
riveted  to  the  transverse  flange  of  the  frame  and  the  two 
combined  act  as  a  girder  in  supporting  the  shell  plating, 
the  two  transverse  flanges  forming  the -web,  and  the  reverse 


STRUCTURAL  MEMBERS  OF  SHIPS 


81 


frame  furnishing  additional  flange  strength.  The  use 
of  channels,  bulb  angles  or  Z-bars  accomplishes  a  similar 
result  without  so  much  riveting. 

For  even  greater  strength  a  plate  may  be  introduced 
between  the  frame  and  reverse  frame,  thus  giving  a  deeper 


Shell 
Plating 


FRAME  AND  REVERSE   FRAME 
(SECTION  A  B,   FIG.   23) 


Shell 
Plating 


Shell 
Plating 


Rev.  Frame 


FLOOR  PLATE 
(SECTION  CD,   FIG.  25) 


Shell 
Plating 


BULB  ANGLE  FRAME 


Z-BAR  FRAME 


Fia.  24. — Transverse  framing. 


web  and  increasing  the  strength  of  the  whole  as  a  girder. 
This  construction  is  also  illustrated  in  Fig.  24.  Such  plates 
are  usually  fitted  between  the  frames  and  reverse  frames 
over  the  bottom  shell  plating  in  order  to  reinforce  and  stiffen 
the  bottom  of  the  ship,  and  are  then  called  floor  plates. 
Floor  plates  have  the  same  depth  as  the  centre  vertical 


82 


PRACTICAL  SHIP  PRODUCTION 


keel  at  the  centre  line  of  the  ship  and  are  reduced  in  depth 
about  uniformly  from  the  centre  until  at  or  near  the  turn 
of  the  bilge  the  depth  becomes  the  same  as  that  of  the  trans- 
verse flange  of  the  frame  bar,  and  they  are  terminated. 
A  similar  construction  is  found  in  web  frames  (also  called 
deep  frames  or  belt  frames)  in  which  the  full  depth  of  the 


Bracket  for  attachment . 
of  deck  beam 


-  Floor  Plate  cut  off  at  corners 
to  clear  top  and  bottom  angles 
of  Centre  Vertical  Keel. 


J4 B 

See  Eig.24J 


utboard  end 
of  Floor  Plate 


Frame  Angle 


-  Floor  Plate 

"Clip  to  connect  Floor  Plate 
to  Centre  Vertical  Keel 

FIG.  25. — Frame,  reverse  frame,  and  floor  plate. 

web  plate  is  maintained  throughout  the  entire  girth  of  the 
frame.  These  are  special  frames  fitted  to  give  great 
transverse  strength,  and  occur  at  intervals  of  a  number  of 
frame  spaces  apart.  They  may  be  considered  as  partial 
bulkheads. 

Ih  Fig.  25  is  shown  a  transverse  frame,  reverse  frame 
and  floor  plate,  the  section  at  AB  being  the  same  as  that 


STRUCTURAL  MEMBERS  OF  SHIPS  83 

of  the  frame  and  reverse  frame  shown  in  Fig.  24,  and  at  CD 
as  that  of  the  floor  plate  in  Fig.  24.  (The  bevel  of  the  frame 
and  reverse  frame  angles  is  not,  however,  indicated  in 
Fig.  25.)  Referring  to  Fig.  25  the  following  points  will 
be  noted.  The  outboard  or  tapered  end  of  the  floor 
plate  is  bent,  in  its  own  plane,  to  the  curvature  of  the 
frame  and  reverse  frame  angle  bars  between  which  it  is 
fitted.  It  is  reduced  in  weight  by  means  of  several  large 
circular  lightening  holes  cut  or  punched  in  it.  At  its  end 
is  fitted  a  tapered  filling-in  piece  or  liner  which  fills  the 
space  between  the  frame  and  reverse  frame  at  their  junction. 
Small  circular  limber  holes  are  cut  in  the  lower  portions  of 
the  floor  plates  in  order  to  permit  water  to  pass  through 
for  drainage.  The  floor  plates  are  fastened  to  the  centre 
vertical  keel  by  means  of  short  pieces  of  angle  bar,  called 
clips  or  lugs.  Brackets,  or  triangular-shaped  plates  are 
fitted  to  give  a  suitable  connection  of  the  beams  to  the 
frames.  The  inboard  corners  of  the  floor  plates  are  cut 
off  sufficiently  to  permit  the  upper  and  lower  angles  of  the 
centre  vertical  keel  to  run  through  continuously. 

In  order  to  prevent  racking,  or  fore  and  aft  movement  of 
the  frames,  reverse  frames,  and  floor  plates,  and  to  tie  them 
together  and  add  to  the  support  that  they  furnish  to  the 
shell  plating  (as  well  as  to  add  to  the  longitudinal  strength 
of  the  ship)  certain  fore  and  aft  members  called  keelsons 
and  stringers  are  fitted  in  addition  to  the  keel  and  centre 
vertical  keel.  These  consist  of  angle  bars,  single  or  double, 
running  along  the  inner  edges  of  the  reverse  bars  and  con- 
nected to  the  shell  plating  by  flat  plates  placed  normally 
to  the  curvature  of  the  molded  surface.  The  number 
and  disposition  of  these  members  depends  upon  the  size 
and  type  of  the  ship. 

Keelsons  run  approximately  or  exactly  parallel  to  the 
centre  vertical  keel.  Those  nearest  the  keel  are  called 
side  keelsons,  and  those  near  the  bilges,  bilge  keelsons,  the 
general  construction  of  both  being  about  the  same.  The 
surfaces  of  these  members  intersect  the  surfaces  of  the  floor 
plates  approximately  at  right  angles,  and  therefore  the 


84  PRACTICAL  SHIP  PRODUCTION 

plate  portions  of  them  must  be  made  in  sections  to  fit 
between  adjacent  floor  plates.  Such  plates  are  called 
intercostal  plates,  the  term  intercostal  being  applied  in 
general  to  any  member  which  is  formed  of  separate  parts 
fitted  between  successive  continuous  members  that  it 
intersects.  In  Fig.  26  is  shown  a  side  elevation  and  cross 
section  of  a  side  keelson  and  also  a  separate  view  of  one 
of  its  intercostal  plates.  The  intercostal  plates  fit  snugly 
against  the  floor  plates  but  are  not  connected  directly  to 


Continuous  Keelson  Angles- 


INTERCOSTAL  PLATE 

FIG.  26. — Intercostal  side  keelson. 

them.  The  keelson  angles  are  tied  to  the  shell  plating  by 
means  of  the  intercostal  plates  which  are  clipped  to  the 
shell.  Along  the  line  of  the  keelson  angles,  which  run 
continuously  along  the  inner  edges  of  the  floor  plates,  are 
fitted  short  lugs,  riveted  to  the  floor  plates  on  the  side 
opposite  the  reverse  frames,  to  give  a  rigid  attachment  for 
the  keelson  angles.  The  frames  and  reverse  frames  are 
continuous  and  pass  through  notches  cut  in  the  intercostal 
plates. 

Stringers  have  a  construction  very  similar  to  that  of 
keelsons,  but  being  located  above  the  outboard  ends  of 
the  floor  plates  (see  Fig.  28)  the  stringer  plates  do  not  have 
to  be  entirely  intercostal  and  are  simply  notched  out  for 
the  frames  and  reverse  frames.  The  construction  of  a 


STRUCTURAL  MEMBERS  OF  SHIPS 


85 


stringer  is  shown  in  Fig.  27,  which  gives  good  continuity 
of  longitudinal  strength.  Stringers  located  near  the  bilge 
are  called  bilge  stringers,  and  those  higher  up,  side  or  hold 
stringers. 

In  Fig.  28  is  shown  a  cross  section  of  a  ship  framed  on  the 
principles  just  described,  that  is,  with  transverse  frames, 
reverse  frames  and  floor  plates,  and  centre  vertical  keel. 
This  figure  is  merely  for  the  purpose  of  indicating  the 
general  construction  and  the  relative  dimensions  are  not 
strictly  accurate.  Only  one  keelson  is  shown,  but  in  a 
larger  ship  several  might  be  fitted  between  the  centre 


Reverse  Frames- 


Shell  Plating 


Frames- 


pyyt       oiip       myi u 

If  \        Continuous         \      Angle 


PLAN 


Stringer  Plate 


FIG.  27. — Side  stringer. 

vertical  keel  and  each  bilge.  It  will  be  noted  that  the 
outboard  deck  plating  which  is  attached  directly  to  the 
shell  also  assists  in  furnishing  longitudinal  strength.  These 
plates  are  usually  made  heavy  for  this  purpose  and  on 
account  of  their  function  are  called  deck  stringer  plates. 
Girders  are  also  fitted  under  the  decks,  as  shown  in  the 
figure,  which,  together  with  the  deck  stringers  and  upper 
portion  of  the  shell  plating  give  longitudinal  strength  to 
the  upper  ''flange"  of  the  ship,  considered  as  a  girder. 

Ships,  except  very  small  ones,  are  usually  fitted  with 
double  bottoms  so  that  the  construction  of  the  lower  por- 
tion is  somewhat  different  from  that  shown  in  Fig.  28. 
The  double  bottom  is  formed  by  fitting  plating  over  the 
tops  of  the  floor  plates  and  curving  it  down  at  the  sides  to  join 
the  shell^plating.  In  this  case  the  depth  of  the  floor  plates 


86 


PRACTICAL  SHIP  PRODUCTION 


is  maintained  nearly  constant  from  bilge  to  bilge  and  the 
inner  bottom  is  usually  flat  and  horizontal.  The  continu- 
ous keelson  angles  shown  in  Fig.  26  are  omitted  and  the 
keelson  plates  extended  only  to  the  tops  of  the  floor  plates. 


Deck  stringer  plate 


'Lightening:  ho 

Centre 
Vertical  Keel 


Shell  plating 


Frame 


"Clip  or  lug 
Flat  Plate  Keel 


Floor  Plate 


FIG.  28. — Cross  section  of  a  ship  showing  longitudinal  framing. 

They  are  given  sufficient  strength  to  make  up  for  this  re- 
duction by  the  inner  bottom  plating  to  which  their  upper 
edges  are  now  attached.  Instead  of  being  called  keelsons 
they  are  then  spoken  of  as  longitudinals. 


Floors 


2d  Longitudinal  starb'd 
\  <s\  \ 

\  \  1st  Longitudinal  (starb'd) 

\  Centre  Vertical  Keel 

1st  Longitudinal  (port) 
FIG.  29. — Diagrammatic  view  of  cellular  double  bottom  framing. 

The  floor  plates  and  longitudinals  intersecting  at  right 
angles  form  a  cellular  double  bottom  composed  of  a 
greatjnany  rectangular  pockets  or  cells  as  shown  in  per- 
spective in  Fig,  29.  This  construction  is  found  in_nearly 


STRUCTURAL  MEMBERS  OF  SHIPS 


87 


all  modern  ships  of  any  size.  In  war  ships  the  double 
bottom  is  continued  farther  up  the  sides  of  the  ship  the 
longitudinals  being  then  more  numerous  and  being  as  nearly 
normal  to  the  inner  and  outer  plating  as  possible.  In  large 
merchant  passenger  ships  a  similar  construction  has  been 
adopted  in  recent  years  (since  the  loss  of  the  " Titanic"). 


Margin 
Plate 


olid 


/  Bracket 


.  Inner  I  Bottom, 


Bracket  \ 


^ 

Nl 

Til  ,  , 

^Centre!  Vertical  teel         ^ 

Margin 
Plate 


Longitudinals 


e      Bott 


"  Outer  Bottom 
(.Shell  Plating) 


Longitudinals 


FIG.  30. — Cross  section  of  double  bottom, 

The  ship  is  thus  given  two  complete  under  water  shells, 
which  greatly  increase  her  safety  in  the  event  of  collision 
or  grounding. 

For  ordinary  merchant  cargo  vessels,  however,  the  double 
bottom  is  continued  only  to  the  bilges,  where  the  inner 


_Centre  Line  of  Ship 


;ntre  Vert.  Keel  (Continuous) 
^.Reverse  Frame  (Continuous) 


Bracket. 
Margin  Plate. 


-She\\  Plating. 
-Intercostal  Longitudinals 
FIG.  31. — Cross  section  of  cellular  double  bottom  with  intercostal  longitudinals. 

bottom  is  connected  to  the  outer  bottom  by  a  margin  plate 
placed  normal  to  the  shell  plating.  The  arrangement 
is  shown  in  Fig.  30.  Each  frame  is  tied  to  the  floor  plate 
within  the  inner  bottom  by  means  of  a  bracket  as  shown. 

The  details  of  the  construction  are  shown  in  Fig.  31  which 
represents  a  typical  double  bottom  of  a  merchant  cargo 


88 


PRACTICAL  SHIP  PRODUCTION 


vessel,  in  cross  section.  Re/erring  to  this  figure  it  will 
be  noted  that  the  floor  plates  are  continuous  from  centre 
vertical  keel  to  margin  plate  while  the  longitudinal  plates 
and  their  upper  and  lower  angles  are  intercostal.  In 
Fig.  29  the  line  FGHK  represents  the  top  of  a  single  con- 
tinuous floor  plate  of  this  type  and  the  longitudinals  are 
composed  of  a  number  of  short  rectangular  sections,  the 
tops  of  which  are  AB,  BC,  CD,  DE,  etc.  These  short 
longitudinal  plates  are  attached  by  clips,  or  lugs,  to  the 
floor  plates  between  which  they  are  fitted,  as  shown  in 
Figs.  31  and  32.  The  margin  plate  is  flanged  over  at  its 
upper  edge  to  form  a  lap  joint  with  the  outer  edge  of  the 


Reverse 
Frames  (Cont.)  \ 


Inner  Bottom  Plating 


-Shell  Plating 

FIG.  32. — Longitudinal  section  of  cellular  double  bottom  showing  intercostal 

longitudinal. 


inner  bottom  plating  and  is  connected  on  its  inboard  and 
outboard  sides  to  the  floor  plates  and  brackets,  respectively, 
by  angle  clips,  as  shown  in  Fig.  31. 

Fig.  32  is  another  section  through  the  double  bottom, 
taken  fore  and  aft,  or  at  right  angles  to  the  section  shown 
in  Fig.  31,  and  shows  how  the  plates  of  the  longitudinals 
are  cut  off  at  the  corners  to  permit  the  continuous  frame 
and  reverse  frame  angles  to  pass  through. 

The  construction  shown  in  Figs.  31  and  32  is  used  in 
warships,  with  the  exception,  however,  that  the  longitudinal 
plates  and  their  upper  angles  run  continuously  and  the 
floor  plates  are  intercostal  between  them,  the  frame  angles, 
however,  being  still  kept  continuous.  Such  floor  plates 


STRUCTURAL  MEMBERS  OF  SHIPS 


89 


(although  lightened  by  large  holes)  are  spoken  of  as  solid 
floors. 

It  is  customary  to  replace  some  of  the  solid  floors,  both 
in  merchant  vessels  and  in  warships,  by  bracket  floors, 
which  reduce  the  weight  and  still  give  sufficient  strength. 


Upper  angle  of 
longitudinal  (Cont.) 


Longitudinals  (Cont.)v 


Inner  Bottom 


Lower  angle  of 
longitudinal  (Intercostal) 


Frame J      angle       []  (C??t- ). 

i^^^HH^^BBM^ 

Outer  Bottom' 
FIG.  33. — Bracket  floor. 


A  bracket  floor  as  fitted  in  warships  is  shown  in  Fig.  33. 
The  continuity  of  the  longitudinal  plates  and  their  upper 
angles  and  of  the  frame  angles  will  be  noted  here,  this 
being  typical  of  warship  construction. 

At  the  ends  of  double  bottom  tanks  (which  usually  come 
under    athwartship    bulkheads)    solid    water-tight    floors 


Vort.Keal          /Inner  Bottom  Plating 


Margin  Plate 


x  Bottom  Plating 
FIG.  34. — Watertight  floor,  cut  by  continuous  longitudinals. 

are  fitted.  These  are  nothing  but  extensions  of  the  bulk- 
heads above,  or  if  there  are  no  bulkheads  above  may  be 
considered  as  partial  bulkheads  themselves.  Such  a 
water-tight  floor  is  shown  in  Fig.  34,  in  which  the  special 
stapling  of  the  bounding  angle  bars,  in  order  to  make  the 
connections  water-tight,  should  be  noted. 


90  PRACTICAL  SHIP  PRODUCTION 

Limber  holes,  air  holes  and  drain  holes  are  cut  in  longi- 
tudinals and  floors  in  order  to  permit  water  to  be  pumped 
in  or  out  of  the  double  bottom  tanks  through  which  they 
pass.  See  Figs.  31  and  32.  Limber  holes  are  usually  about 
3"  in  diameter  and  located  tangent  to  the  upper  edge 
of  the  frame.  Drain  holes  (not  shown  in  the  figures) 
are  smaller,  about  2"  long  X  1"  high,  cut  through  both 
floor  and  frame  (or  longitudinal  and  its  lower  angle) 
just  over  the  bottom  flange.  Air  holes  are  similar  to  drain 
holes,  only  that  they  should  be  located  as  high,  instead 
of  as  low  as  possible.  Sometimes  larger  air  holes  are  also 
cut  resembling  limber  holes  but  cut  in  the  upper  part  of  the 
floors  or  longitudinals. 

At  the  ends  of  the  ship,  where  longitudinal  strength  is 
not  so  important,  the  framing  is  different  from  that  in  the 
middle  body.  Keelsons,  stringers,  etc.,  are  often  omitted 
here  and  the  transverse  frames  are  fitted  with  very  deep 
floor  plates  which  give  great  stiffness  to  the  shell  plating. 
At  the  bow  special  horizontal  plates  called  breast  hooks, 
and  sometimes  vertical  ram  plates  are  attached  to  the  shell 
to  stiffen  it  against  panting.  These  usually  form  the  termi- 
nations of  keelsons  or  longitudinals.  Panting  stringers  are 
also  often  fitted.  In  merchant  ships  the  framing  aft  of  the 
stern  post  is  usually  arranged  radially  so  as  to  be  normal  to 
the  plating.  Such  frames  are  called  cant  frames. 

The  preceding  description  of  transverse  and  longitudinal 
framing  applies  to  what  is  commonly  known  as  the  transverse 
system  of  framing,  which  is  the  system  most  often  used. 
Only  a  few  representative  constructions  have  been  described 
and  it  must  be  remembered  that  there  is  practically  no 
limit  to  the  number  of  various  special  designs  for  framing 
that  may  be  found  in  use.  Those  that  have  been  described 
will  serve  to  give  an  idea  of  the  objects  to  be  attained,  and 
of  some  of  the  ordinary  constructions,  from  which  others 
may-  be  developed. 

Another  system  of  framing  that  has  come  into  quite 
considerable  use  in  recent  years  is  the  Isherwood  System, 
sometimes  called  the  longitudinal  system,  In  this  the  main 


STRUCTURAL  MEMBERS  OF  SHIPS  91 

framing  runs  fore  and  aft  and  the  transverse  members  form 
the  auxiliary  framing,  being  spaced  at  greater  intervals 
than  in  the  so-called  transverse  system.  As  a  matter 
of  fact  in  the  Isherwood  system  the  transverse  members 
are  heavier,  but  continuity  of  all  the  longitudinal  members 
is  attained.  A  cross-section  of  an  Isherwood-built  ship 
resembles  that  of  a  ship  with  a  large  number  of  keelsons, 
stringers  and  girders,  and  deep  or  web  frames.  This  con- 
struction is  especially  well  adapted  to  oil  tankers,  for  which 
it  is  now  almost  universally  used. 

2.  STEM,  STERN  POST,  RUDDER,  ETC. 

The  lines  of  a  ship  at  the  ends  gradually  taper  off  to  the 
"cutwater  "  at  the  bow  and  to  the  rudder  post  at  the  stern. 
The  keel,  which  is  usually  straight  and  horizontal  for  nearly 
the  complete  length  of  the  ship  merges,  near  the  bow, 
into  the  stem,  and  near  the  after  end,  into  the  stern  post 
or  stern  frame.  The  nature  of  these  members  varies  with 
the  type  of  ship.  In  war  ships,  which  usually  have  specially 
shaped  bows  and  sterns  (see  Fig.  19),  they  are  elaborate 
steel  castings,  often  made  in  more  than  one  piece.  In 
merchant  ships  they  are  usually  of  simpler  form  and  may  be 
of  wrought  iron  or  steel.  In  either  case  they  serve  to 
form  continuations  of  the  keel,  finishing  off  the  ends  of 
the  ship  and  providing  a  suitable  means  for  the  attachment 
of  the  shell  plating. 

Stem. — The  stem  may  be  considered  as  the  forward 
end  of  the  keel,  bent  up  and  extended  in  a  vertical  or  nearly 
vertical  line.  In  its  simplest  form  it  consists  of  a  bar  of 
the  same  cross  section  as  the  keel  (when  the  latter  is  a 
bar  keel)  attached  thereto  by  means  of  long  through  rivets, 
the  joint  being  formed  by  cutting  away  a  portion  of  both 
keel  and  stem  bars  so  that  they  may  overlap  each  other 
without  increasing  the  width  of  either.  Such  a  joint  is 
called  a  scar  ph.  A  stem  of  this  type  is  shown  in  the  right 
hand  sketch  of  Fig.  35.  If  of  this  simple  form  it  would 
ordinarily  be  a  forging.  The  ends  of  the  shell  plating  are 
flanged  and  riveted  to  it  just  as  to  the  bar  keel. 


92 


PRACTICAL  SHIP  PRODUCTION 


A  bar  stem  may  also  be  used  in  conjunction  with  a  flat 
plate  keel,  in  which  case  the  lower  portion  is  gradually 
flattened  out  so  as  to  fit  into  the  last  U-shaped  plate  of 
the  plate  keel  and  is  given  a  vertical  fin  or  web  on  its  upper 
surface  for  the  attachment  of  the  centre  vertical  keel. 
On  account  of  the  difficulty  of  forging  this  lower  portion 


Bar  Keel 
FIG.  35. — Stern  post  and  stem. 

such  a  keel  might  be  made  in  two  parts,  the  lower  one 
being  a  steel  casting  and  the  upper  one,  scarphed  to  the 
lower,  a  forging.  A  cross  section,  normal  to  its  curvature, 
of  the  lower  portion  of  such  a  keel  is  shown  in  Fig.  36. 
The  shell  plating  is  recessed,  or  rabbetted,  into  the  keel, 


STRUCTURAL  MEMBERS  OF  SHIPS 


93 


so  that  its  outer  surface  will  be  flush  with  the  outer  surface 
of  the  keel,  as  shown. 

For  warships  the  stem  is  ordinarily  formed  of  two  steel 
castings  scarphed  together  at  a  point  above  the  water  line 
and  made  with  webs  or  lugs  for  the  attachment  of  decks, 
longitudinals,  floor  plates,  etc.  For  extra  strength  the 
shell  plating  is  doubled,  the  outer  layer  overlapping  the 
inner  so  that  a  rabbett  of  two  steps  is  necessary  in  the  stem 
casting.  Heavy  breast  hooks  and  ram  plates  are  also 


Centre  Vertical  Keel 


Shell  Plating 


Rabbet 


Stem  Casting 
FIG.  36. — Cross  section  of  lower  portion  of  cast  stem. 

attached  to  it.  Such  a  stem  being  of  complicated  form 
must  be  a  casting. 

The  stem  of  a  sheathed  vessel  is  made  of  manganese  or 
phosphor  bronze,  so  as  to  prevent  galvanic  action. 

Stern  Post. — Like  the  stem,  the  stern  post  may  also  be 
considered  as  an  extension  of  the  keel,  bent  up  vertically. 
It  is,  however,  more  complicate!!  on  account  of  the  support 
that  it  must  furnish  to  the  rudder,  and,  usually,  to  the 
propeller.  With  a  bar  keel  the  simplest  type  may  be 
forged  and  of  a  form  similar  to  that  shown  in  Fig.  35. 
Such  a  stern  post  (or  stern  frame)  might  also  be  cast,  and 


94  PRACTICAL  SHIP  PRODUCTION 

with  more  complicated  constructions  it  is  almost  invariably 
so  made.  As  shown  in  Fig.  35,  the  stern  frame  consists 
of  the  rudder  post  and  body  post  with  an  opening  between 
for  the  screw  or  propeller.  The  rudder  post  has  projections 
or  lugs,  called  gudgeons,  which  serve  as  bearings  for  vertical 
pins  attached  to  lugs  on  the  rudder,  and  called  pintles. 
The  body  post,  to  which  is  attached  the  shell  plating,  in 
the  same  manner  as  to  the  stem,  serves  in  single  or  triple 
screw  ships,  as  a  support  for  the  after  end  of  the  propeller 
shaft,  being  swelled  out  and  provided  with  a  longitudinal 
hole  or  opening  for  that  purpose.  It  is  sometimes  also 
called  the  propeller  post,  in  such  cases.  In  twin  or  quad- 
ruple screw  ships  the  stern  post  is  also  the  rudder  post  and 
there  is  no  screw  aperture,  the  shell  plating  extending 
right  aft  to  the  rudder  post,  as  a  rule.  Such  a  construction 
is  shown  in  Fig.  18.  When  fitted  in  connection  with  a  bar 
keel  the  stern  frame  is  scarphed  to  it,  like  the  stem,  as 
shown  in  Fig.  35.  If  fitted  with  a  flat  plate  keel  a  casting 
formed  similarly  to  the  stem  casting  shown  in  Fig.  36 
would  ordinarily  be  used. 

For  war  ships  the  stern  post  is  usually  an  elaborate  steel 
casting  made  in  two  or  more  parts  made  with  webs,  lugs, 
rabbetts,  etc.,  in  a  manner  similar  to  the  stem.  Its  shape 
is  quite  different  from  that  ordinarily  used  for  merchant 
vessels  on  account  of  the  larger,  balanced  rudder,  and  the 
necessity  for  keeping  the  rudder  head  and  steering  gear 
below  the  water  line  where  they  are  less  liable  to  be  damaged 
in  action. 

Recently  some  merchant  vessels  have  been  built  with 
"cruiser  sterns/7  or  sterns  of  the  typical  war  ship  form. 
The  various  possible  combinations  and  arrangements  of 
rudders  and  propellers  have  resulted  in  a  variety  of  forms 
of  stern  posts,  all  requiring  special  castings,  designed  to 
meet  the  particular  needs.  In  all  cases  it  is  necessary 
that  both  the  stern  post  and  stem  be  strongly  secured  to 
the  shell  plating  and  hull  structure  in  their  vicinity,  in 
order  properly  to  transmit  to  the  hull  the  forces  due  to 


STRUCTURAL  MEMBERS  OF  SHIPS 


95 


steering,    propulsion    and    possible    head-on    collision    or 
ramming. 

Rudders. — A  rudder  consists  of  the  main  flat  portion, 
or  blade,  and  the  vertical  shaft  or  stock.  The  upper  end  or 
continuation  of  the  stock  above  the  blade  is  called  the 
rudder  head.  Rudders  may  be  of  the  simple  unbalanced 


Rudder  Head  ( Forging  ) 


Coupling 


FIG.  37. — Solid  cast  rudder. 

type  (as  ordinarily  fitted  to  merchant  vessels),  of  the 
simple  balanced  type,  balanced  type  partially  underhung 
or  balanced  type  completely  underhung.  Balanced  rudders 
are  used  for  war  ships  almost  exclusively,  being  necessary 
to  give  quick  turning  ability  without  the  use  of  an  exceed- 
ingly powerful  steering  engine.  The  warship  in  Fig.  19 


96  PRACTICAL  SHIP  PRODUCTION 

has  a  partially  underhung,  balanced  rudder.  The  merchant 
vessel  and  yacht  in  the  same  figure  have  unbalanced 
rudders. 

As  regards  construction' rudders  have  a  great  variety  of 
forms,  depending  upon  the  size  and  type  of  ship,  and  the 
cost  of  manufacture.  The  simplest  is  the  solid  blade  cast 
in  a  single  piece  as  shown  in  Fig.  37.  Owing  to  the  difficulty 
of  obtaining  such  a  casting  without  having  it  more  or  less 
warped  rudders  of  this  type  are  made  only  in  small  sizes. 
The  rudder  head  is  always  a  forging  in  order  to  provide 
the  necessary  strength  to  take  the  torsional  stresses.  The 
stresses  increase  from  the  bottom  of  the  stock  toward  the 
head,  and  decrease  from  the  stock  aft  to  the  after  curved 
edge  or  bow  of  the  blade.  Hence  the  stock  tapers  from 
head  to  heel  and  the  blade  from  stock  to  after  edge,  as 
shown.  Projections  or  snugs  are  cast  on  the  forward  edge 
of  the  stock  to  take  the  pintles,  or  pins  upon  which  the 
rudder  hinges. 

A  development  of  the  simple  cast  rudder  is  the  single 
plate  rudder  which  consists  of  a  single  heavy  plate  cut 
to  the  proper  contour  and  secured  to  the  stock  by  means  of 
arms  on  either  side  to  which  the  plate  is  riveted.  A  rudder 
of  this  type  is  shown  in  Fig.  38,  The  arms,  which  are 
usually  forgings  (although  sometimes  they  are  of  cast 
steel)  are  made  separately  and  shrunk  on  to  the  stock,  which 
is  also,  as  a  rule,  a  forging.  The  rudder  head  is  bolted  to 
the  rudder  stock  by  means  of  a  flat  keyed  flanged  coupling 
as  shown.  Notches  are  cut  in  the  plate  to  fit  around  the 
arms  at  the  stock.  The  arms  are  keyed  to  the  stock. 
In  order  to  limit  the  angle  through  which  the  rudder  may 
be  put  over  stops  are  provided  on  one  of  the  snugs  on  each 
side,  as  shown,  designed  to  take  up  against  corresponding 
ones  on  the  stern  of  the  ship. 

This  type  of  rudder  has  the  advantages  of  great  strength, 
ease  of  construction  and  accessibility  of  all  parts  for  cleaning 
and  painting.  The  arms  may  also  be  forged  or  cast  onto 
the  stock. 

In  warships,  and  some  merchant  ships  which,  on  account 


STRUCTURAL  MEMBERS  OF  SHIPS 


97 


of  their  specially  formed  sterns,  have  more  complicated 
rudders,  the  rudder  consists  of  a  frame,  forged  or  cast 
of  steel  (usually  the  latter)  and  covered  on  each  side  with 
light  plating.  The  spaces  between  the  ribs  or  arms  of  the 
frame  are  filled  with  some  light  wood,  such  as  fir,  spruce, 
or  white  pine,  embedded  in  pitch  or  red  lead  paste,  or 
with  cement,  coke,  etc.  Such  a  rudder  of  the  simple 


-Rudder  Head 
-Coupling  or  Joint 


FIG.  38. — Single  plate  built  up  rudder. 

unbalanced  type  is  shown  in  Fig.  39.  (The  general 
principles  of  construction  of  a  balanced  rudder  are  much 
the  same.) 

The  pintles  of  practically  all  rudders  turn  in  holes  in 
lugs  on  the  stern  or  rudder  post,  called  gudgeons.  In 
cheaply  constructed  ships  there  are  no  special  bushings  or 
sleeves  between  the  iron  or  steel  of  the  pintles  and  the 
gudgeons,  but  in  large  well-built  ships  the  construction  is 


98 


PRACTICAL  SHIP  PRODUCTION 


similar  to  that  shown  in  Fig.  40,  the  pintle  being  surrounded 
by  a  composition  bushing  in  the  gudgeon  hole,  with  a  conical 
socket  or  washer  of  steel  underneath.  In  very  high-class 
work  there  are  bronze  sleeves  fitted  over  the  pintles,  and 
bushings  in  the  gudgeons — sometimes  fitted  with  vertical 
strips  of  lignum  vitse  set  in  white  metal. 


Spaces  filled  with  Wood 
Both  sides  plated  over 

FIG.  39. — Cast  frame  of  side  plate  rudder. 

In  merchant  vessels  the  upper  portion  of  the  rudder 
stock,  or  rudder  head,  where  it  passes  through  the  hull 
is  encased  in  a  water  tight  tube  or  trunk  fitted  with  a 
stuffing  box  either  just  above  the  plating  of  the  counter 
or  at  the  lowest  deck  above  the  counter.  In  some  cases 
no  stuffing  box  is  fitted,  the  trunk  being  carried  all  the 
way  up  to  the  weather  deck. 


STRUCTURAL  MEMBERS  OF  SHIPS 


99 


The  plating  of  the  counter  in  merchant  ships  being 
normally  some  distance  above  the  water  line,  water- 
tightness  is  not  so  important,  but  is  nevertheless  required 
to  prevent  water,  caused  by  the  splashing  of  waves  or 
due  to  excessive  trim  by  the  stern,  from  entering  the  hull. 

In  warships  the  counter  is  usually  below  the- water  line, 
and  in  addition  to  this  it  is  ordinarily  necessary  to  take  the 
weight  of  the  rudder  inside  of  the  ship.  The  construction 
is  therefore  considerably  different  from  merchant  ships, 


Rudder   (Cast  Steel) 


Pintle 
(Wrought  Steel) 


Gudgeon 


Snug 


Bushing 
(Composition) 


Cone  Socket 
(Wrought  Steel) 


FIG.  40. — Pintle. 

an  elaborate  stuffing  box  being  fitted  to  the  stern  casting, 
combined  with  a  carrier  which  takes  the  weight  of  the 
rudder.  The  general  arrangement  of  such  a  rudder  head 
stuffing  box  and  rudder  carrier  is  shown  in  Fig.  41.  A 
portion  of  the  rudder  head  is  covered  by  a  bronze  sleeve, 
shrunk  on.  Water  is  kept  out  by  means  of  a  stuffing  box 
and  gland,  operated,  as  shown,  by  means  of  a  nut  gearing 
with  a  worm.  Both  gland  and  nut  are  made  in  parts  so  as 
to  be  removable  through  holes  in  the  side  of  the  carrier 


100 


PRACTICAL  SHIP  PRODUCTION 


casting.  Instead  of  a  tiller  an  athwartship  yoke  is  fitted 
for  turning  the  rudder.  An  annular  key  transmits  the 
weight  to  the  carrier. 

Stern  Tubes,  Propeller  Struts,  Etc. — In  ships  fitted 
with  propellers  special  means  must  be  provided  to  permit 
the  shaft  which  turns  the  propeller  to  pass  through  the 
skin  of  the  ship  or  outer  hull  in  such  a  manner  that  it  may 
revolve,  and  at  the  same  time  to  prevent  water  from  enter- 


Brake 


Zinc  Protector 


Weight  of 
Rudder 


Keys 


Bearing  Ring 
Carrier  Casting 

Nut 


Stern  Frame 
Casting 


Rudder  Head  Sleeve 

udder  Head 
or  Stock 


FIG.  41. — Rudder  carrier,  etc. 

ing  around  it  into  the  ship.  In  order  to  accomplish  this 
the  shaft,  where  it  leaves  the  ship's  main  hull,  is  supported 
in  a  specially  constructed  bearing  fitted  in  a  stern  or  shaft 
tube. 

Steam  propelled  vessels  usually  have  one,  two,  three,  or 
four  propellers  being  designated  accordingly  as  single, 
twin,  triple,  or  quadruple  screw  vessels  respectively.  If 
the  number  of  propellers  is  odd  one  of  the  shafts  is  located 


STRUCTURAL  MEMBERS  "OF  SHIPS 


101 


along  the  centre  line  of  the  ship  and  passes  through  a  large 
cylindrical  hole  in  the  stern  post  which  is  bossed  out  to 
receive  it  (see  Fig.  35).  If  the  number  of  propellers  is 
more  than  one,  those  not  located  on  the  centre  line  are 
placed  symmetrically  with  respect  to  the  centre  line  and  are 
called  wing  propellers.  The  wing  shafts  usually  run  nearly 


Floor  Plate 


Stern  Tube 


-Floor  Plate 


^  P — Stern  Frame 


Frarafe  No.l 
_(  Looking  Forward) 

FIG.  42. — Bossing  and  stern  framing. 


Portion  of 
Body  Plan 


but  not  quite  parallel  to  the  vertical  longitudinal  centre 
line  plane  of  the  ship.  Whether  the  shaft  is  a  centre  or  a 
wing  shaft  it  usually  is  inclined  slightly  to  the  horizontal, 
its  after  end  being  the  lower. 

There  are  in  general,  then,  two  types  of  shafts  to  consider : 
(1)  centre  shafts,  and  (2)  wing  shafts. 

Centre  Shafts. — In  order  to  give  sufficient  room  for  the 
shaft  and  its  tube  and  bearing  the  molded  form  of  the 
ship  in  the  vicinity  of  the  stern  post  and  fine  portion  of 
the  run  must  be  swelled  out  or  bossed  as  shown  in  Fig.  42. 


102  :PRACTICAL  SHIP  PRODUCTION 

This  shows  the  lower  after  portion  of  the  body  plan  of  a 
single  screw  or  triple  screw  ship.  The  form  that  the  frames 
would  have  if  they  were  not  bossed  is  shown  by  the  dotted 
lines.  The  shape  of  a  transverse  section  of  the  stern 
frame  is  marked  "O."  The  general  construction  of  the 
frames  in  the  fine  after  portion  of  the  ship  is  indicated  in 
the  right-hand  sketch  in  Fig.  42,  which  represents  the 
details  of  frame  No.  1  of  the  left-hand  sketch.  A  very 
strong  transverse  construction  is  necessary  in  this  portion 
of  the  ship  in  order  to  take  the  stresses  due  to  the  centrifu- 
gal force  and  vibrations  set  up  by  the  revolution  of  the 
propeller.  This  is  provided  by  means  of  deep  floor  plates, 
as  shown,  and  the  shell  plating  in  this  vicinity  is  made 
extra  heavy  or  is  doubled. 

The  large  hole  in  the  stern  post  is.  bored  out  to  take  the 
after  end  of  the  stern  tube,  the  forward  end  of  which  is 
secured  to  a  heavy  transverse  water-tight  bulkhead  (usually 
the  forward  bulkhead  of  the  after  peak).  The  stern  tube 
is  ordinarily  a  thick  cast  steel  tube  through  which  the 
propeller  shaft  passes.  It  is  described  in  detail  below. 

Wing  Shafts. — In  the  case  of  a  shaft  passing  through  the 
molded  surface  at  some  distance  out  from  the  centre 
line  the  shapes  of  the  frames  are  somewhat  similar  to  those 
shown  in  the  upper  sketch  of  Fig.  43,  and  the  shape  of  the 
section  of  the  molded  surface  by  the  horizontal  plane  A  B 
is  similar  to  that  of  the  full  line  in  the  lower  sketch.  The 
frames  are  bent  to  the  shapes  shown  and  are  well  stiffened 
by  plates  arranged  somewhat  similarly  to  the  floor  plates 
shown  in  Fig.  42.  The  shaft  tube  in  this  case  is  fitted  at  the 
after  end  of  the  bossing. 

There  are  two  methods  of  construction  in  the  case  of  wing 
shafts:  (1)  the  bossing  may  be  carried  all  the  way  aft 
to  the  propeller  (as  shown  in  Fig.  43),  or  (2)  the  bossing 
may  be  terminated  considerably  further  forward  and  nearer 
the  main  portion  of  the  hull. 

In  the  first  case  the  frames  extend  out  to  form  a  sort  of 
fin,  terminated  by  the  boss,  this  fin  being  about  normal 
to  the  main  curvature  of  the  frames.  Such  frames,  on 


STRUCTURAL  MEMBERS  OF  SHIPS 


103 


account  of  their  shape,  are  often  called  spectacle  -frames. 
The  shell  plating  is  continued  to  the  after  end  of  this  fin 
and  boss  as  shown  in  Fig.  43,  and  is  terminated  there  by  a 
heavy  steel  casting  or  shaft  bracket.  This  bracket  may  'be 
made  in  a  variety  of  different  ways  but  its  function  is  to 
form  a  termination  of  the  fin  and  bossed  shell  plating  and  to 
furnish  a  strong  and  rigid  support  for  the  shaft  tube  which 
is  fitted  to  its  outer,  swollen  end  in  practically  the  same 
manner  that  the  stern  tube  is  fitted  in  the  stern  post  casting. 
A  cross  section  of  the  shaft  bracket  would  have  the  form 


SECTION  ON  A  B 
FIG.  43. — Bossing  of  a  twin  screw  vessel. 

shown  for  frame  No.  3  in  Fig.  43,  but  it  extends  well  inside 
of  the  hull  where  it  is  rigidly  secured  to  the  ship's  structure 
by  webs  and  flanges  cast  on  it. 

In  the  second  case,  or  that  in  which  the  bossing  does  not 
extend  much  beyond  the  main  hull,  the  shape  of  the  last 
bossed  frame  is  similar  to  frame  No.  6  of  Fig.  43,  and  the 
shaft  tube  is  fitted  at  the  termination  of  this  bossing.  The 
shaft,  however,  extends  for  some  distance  aft  of  the  stern 
tube  and  has  another  bearing  just  forward  of  the  propeller 
supported  by  two  struts.  The  struts  are  heavy  steel 


104 


PRACTICAL  SHIP  PRODUCTION 


Shell  Plating 


members  cast  in  one  with  the  bearing  of  the  shaft  and 
suitably  attached  to  the  hull.  A  simple  type  of  strut 
is  shown  in  Fig.  44.  Various  developments  of  such  struts 
are  in  use,  differing  principally  in  the  means  by  which 
attached  to  the  ship's  hull.  The  bushing  fitted  inside 
of  the  hub  is  similar  to  that  in  the  stern  tube,  i.e.,  lignum 
vitse  strips  set  in  composition. 

In  any  case — whether  the  shaft  passes  through  the  stern 
casting,  or,  if  a  wing  shaft,  whether  spectacle  frames  com- 
bined with  a  shaft  bracket,  or  struts  are  used — the  portion 

of  the  hull  at  which  the  shaft 
leaves  is  fitted  with  a  stern  or 
shaft  tube  bearing.  While  the 
details  of  this  bearing  vary 
somewhat,  the  principal  fea- 
tures are  as  shown  in  the 
Hub  or  strut  sketch  of  Fig.  45. 

The  shaft  itself  (solid  or 
hollow  forged  steel)  is  covered 
by  a  sleeve  of  bronze  or  similar 
composition,  shrunk  on.  The 
shaft  and  sleeve  revolve  in  the 
special  stern  tube  bushing  which 
consists  of  strips  of  lignum  vitse 
(a  very  hard  wood)  imbedded 
in  brass  or  other  composition. 
The  sea  water  has  access  to 
the  longitudinal  spaces  between  these  lignum  vitse  strips 
and  acts  as  a  lubricant  for  the  shaft  (see  cross  section  in 
Fig.  45).  This  bushing  fits  into  the  stern  tube  which  is 
secured  to  the  stern  post  or  shaft  bracket  by  means  of 
a  shoulder  cast  on  it  and  a  large  nut,  as  shown.  The 
forward  end  of  the  stern  tube  has  a  flange  which  is  bolted 
to  a  heavy  transverse  water-tight  bulkhead,  as  shown,  and 
serves  as  a  stuffing  box,  being  provided  with  packing  and 
a  composition  lined  gland.  The  other  details  are  shown  in 
the  figure.  The  stuffing  box  end  of  the  stern  tube  being 


Strut 


CROSS  SECTION 
FIG.  44. — Propeller  struts. 


STRUCTURAL  MEMBERS  OF  SHIPS 


105 


106  PRACTICAL  SHIP  PRODUCTION 

inside  the  ship  can  be  examined,  and  the  gland  set  up  from 
time  to  time  as  necessary. 

In  all  construction  work  in  connection  with  stern  tubes, 
struts,  brackets,  etc.,  the  need  for  great  strength  and  ability 
to  resist  the  shocks  due  to  vibration  is  most  important. 
Rivets  must  be  of  sufficient  size,  proper  spacing  and  of 
first-class  workmanship,  and  framing  and  plating  must 
have  extra  strength.  Zinc  protectors  are  fitted  in  various 
places  to  prevent  excessive  corrosion  due  to  the  galvanic 
action  of  composition  parts  placed  near  steel  parts  in  salt 
water. 

3.  SHELL  PLATING  AND  INNER  BOTTOM 

The  main  essential  of  any  ship  is  the  shell  plating.  This 
forms  the  outer  skin,  keeps  out  the  water,  assists  in  furnish- 
ing strength  and  encloses  all  the  other  main  parts  of  the 
hull.  Its  inner  surface — the  outer  surface  of  the  framing- 
is  the  molded  surface  of  the  ship. 

The  shell  plating  consists  of  a  great  many  steel  plates, 
of  rectangular,  or  nearly  rectangular  shape,  arranged  in 
longitudinal  courses  or  strokes.  The  thickness  of  the 
plates  ranges  from  about  y±'  to  about  I" ',  depending  upon 
the  size  of  the  ship  and  the  particular  location  of  the  plate 
considered. 

There  are  in  general  three  classes  of  plates:  (1)  flat, 
(2)  rolled,  and  (3)  flanged  or  furnaced.  The  first  class, 
which  forms,  usually,  by  far  the  largest  portion  of  the  shell, 
is  made  up  of  those  plates  which  have  little  or  no  curvature 
and  do  not  have  to  be  bent.  Rolled  plates  are  those  having 
a  cylindrical  curvature  only,  and  are  found  principally 
in  the  middle  body  at  the  turn  of  the  bilge.  Flanged 
and  furnaced  plates  are  those  having  special  irregular 
shapes  that  require  special  fashioning — either  after  having 
been  heated  red  hot,  or  in  flanging  machines.  Those  that 
must  be  heated  and  fashioned  to  the  proper  shape  are  called 
furnaced  plates  and  usually  have  curvature  in  three 
dimensions. 

The  strakes  run  parallel  in  the  middle  body  and  gradu- 


STRUCTURAL  MEMBERS  OF  SHIPS  107 

ally  taper  toward  the  ends  of  the  ship.  They  are  commonly 
designated  by  the  letters  A,  B,  C,  D,  etc.,  commencing  with 
the  strake  nearest  the  keel,  which  is  called  the  garboard 
stroke.  The  highest  complete  strake  is  called  the  sheer 
strake,  since  its  upper  edge  has  the  curvature  or  sheer 
of  the  ship.  The  plates  in  each  strake  are  given  serial 
numbers,  commencing  at  the  bow.  Since  the  ship  is 
symmetrical  about  its  longitudinal  central  vertical  plane 
the  plates  of  the  starboard  side  are  duplicates  of  those  of 
the  port  side  except  that  their  curvature,  in  each  case, 
is  reversed.  Each  plate  is  therefore  designated  by  the 
letter  of  the  strake,  the  serial  number  in  that  strake  and 
the  side  of  the  ship.  Example:  "D  11  P,"  means  the 
llth  plate  from  the  bow,  in  the  fourth  strake  from  the  keel, 
on  the  port  side  of  the  ship. 

Plates  around  the  propeller  shafts  are  called  bossed 
plates  and  those  located  where  the  stern  frame  joins  the 
counter  are  called  oxter  plates.  Dished  plates  are  those  of 
U  shaped  cross  section  that  form  the  flat  plate  keel  where  it 
is  flanged  upward  to  connect  to  the  garboard  plates  (See 
Fig.  22)  or  to  the  stem  or  stern  post. 

The  joints  at  the  edges  of  the  strakes  are  called  seams, 
and  at  the  ends  of  the  individual  plates  in  each  strake, 
butts  (see  Fig.  46).  The  edges  of  the  plating  that  are 
visible  from  the  outside  of  the  ship  are  called  sight  edges, 
and  the  intersections  of  both  inner  and  outer  edges  of  the 
plating  with  the  frames  over  which  they  pass  are  called 
landing  edges  (see  Fig.  46). 

There  are  several  different  systems  of  arranging  the  seams 
of  the  shell  plating.  These  are  illustrated  in  Fig.  47. 
The  sunken  and  raised  system  is  used  in  the  vast  majority 
of  cases  on  account  of  its  strength,  simplicity  and  because 
it  is  less  costly  than  some  of  the  other  systems.  The  edges 
of  the  strakes  overlap  each  other.  Parallel  liners  are  fitted 
in  this  system  between  the  fore  and  aft  flange  of  each 
frame  and  all  the  plates  of  the  outer  strakes.  The  clinker 
system  is  somewhat  similar  to  the  sunken  and  raised  system 
(the  seams  being  lapped  in  both)  but  it  requires  the  use  of 


108 


PRACTICAL  SHIP  PRODUCTION 


tapered  liners,  which  increases  the  cost.  It  is,  however, 
somewhat  lighter  than  the  sunken  and  raised,  and  has  the 
added  advantage  that  a  plate  can  be  more  easily  removed 
for  repairs.  The  flush  system  is  little  used,  on  account  of 


the  great  weight  of  liners  and  seam  straps  required.  (All 
strakes  must  have  liners  on  all  frames  and  the  seams  are 
all  strapped  instead  of  lapped.)  It  gives  a  smooth  finished 


STRUCTURAL  MEMBERS  OF  SHIPS 


109 


appearance  and  is  therefore  much  used  for  yachts.  It  is 
also  used  in  cases  where  a  flush  surface  is  necessary  for 
structural  reasons,  as  in  the  case  of  plating  behind  armor. 
Joggling,  which  is  illustrated  in  the  three  right-hand 
sketches  of  Fig.  47  consists  in  offsetting  one  member  that 
fits  against  another  so  as  to  avoid  the  use  of  liners.  In 
two  of  the  sketches  the  edges  of  the  plating  is  shown  as 
j oggled  and  in  the  other  frame  is  j oggled.  This  arrangement 
results  in  a  considerable  saving  in  weight,  but  this  saving 
is^accompaniedjby  a  decrease  in  strength;  and  it  is  usually 
more  costly.  It  is,  of  course,  difficult  to  apply  to  plates 
having  irregular  curvature.  The  system  ordinarily  used  is 
the^sunken  and  raised  system,  which  is  here  considered. 


Frame 


Parallel 
Liner 


SUNKEN 
AND  RAISED 


FRAME 
JOGGLED 


CLINKER          FLUSH  JOGGLED          JOGGLED 

(SUNKEN  AND      (CLINKER) 
RAISED) 

FIG.  47. — Systems  of  sholl  plating. 

The  seams  of  the  shell  plating  for  all  but  the  smallest 
vessels  are  double  riveted,  that  is,  they  contain  two  rows 
of  rivets.  The  inner  rivet  is  omitted  where  it  comes  at  a 
frame,  so  as  not  unduly  to  weaken  the  fore  and  aft  flange. 

The  butts  of  the  plates  may  be  either  lapped  or  butted. 
When  butted  they  usually  have  single  butt  straps  fitted 
on  the  inside.  When  lapped,  the  outer  edge  of  the  lap  is  at 
the  after  end  of  the  plate  so  as  to  decrease  resistance  of  the 
water  when  the  ship  is  moving  ahead.  A  lapped  butt  takes 
up  less  room  in  a  fore  and  aft  direction  than  a  butt-strap 
and  is  stronger,  but  it  is  more  difficult  to  fit,  as  will  be  seen 
by  referring  to  Figs.  48  and  49.  In  these  figures  are  shown 
methods  of  making  the  connections  between  the  two  plates 


110 


PRACTICAL  SHIP  PRODUCTION 


of  one  strake  that  form  the  butt  lap  and  the  plate  of  the 
adjacent  strake. 

The   simplest   method,    and   the   one   most   commonly 
adopted,  is  that  shown  in  Fig.  48.     Here  a  tapered  liner  is 


Tapered  Liner 

Plate 


of  Inner  Strake 


of      Outer  Strake - 


Plate  2  <  \Plate  1 

SECTION  ON    A  A 
FIG.  48. — Butt  lap  with  tapered  liner.     (Seen  from  outside.) 

fitted  to  fill  in  the  triangular  space  between  the  plates  of 
the  inner  and  outer  strakes  caused  by  the  presence  of  the 
lap  butt. 


EdgeN 

Plate  of 
Inner  Strake 

^^                 l 

1  0 

o°i  o 

O    O  !   O     O 

to 

°oj° 

jl                J 

Chamf< 


o  o 


-Plate  1  of 

Outer  Strake 

"(tapered  here) 


Plate  2- 


Plate  1 


SECTION   ON  A  A 
FIG.  49. — Butt  lap — one  plate  tapered  and  chambered.     (Seen  from  inside).) 

A  lighter  and  more  compact  arrangement,  which  does 
away  with  the  need  for  a  liner,  is  shown  in  Fig.  49,  in  which 
the  portion  of  one  plate  that  is  common  to  both  butt  and 
seam  laps  is  tapered  off  and  chamfered.  The  thicknesses 


STRUCTURAL  MEMBERS  OF  SHIPS  111 

are  indicated  in  the  figure  by  "o's"  and."l's,"  "o"  meaning 
no  thickness  and  "  1 "  meaning  the  full  thickness  of  the  plate. 
This  method  is  not  always  employed  on  account  of  the  diffi- 
culty of  tapering  and  chamfering  the  plates,  which,  if  not 
done  by  a  special  machine,  must  be  laboriously  done  by 
hand  chipping.  Furthermore,  it  is  not  desirable  in  the 
case  of  plates  in  inner  strakes  on  account  of  the  difficulty 
of  making  such  a  joint  water-tight.  (Calking  tool  cannot 
be  properly  inserted  in  chamfer.) 

It  will  be  noted  on  referring  again  to  Fig.  46  that  the 
butts  in  the  shell  plating  are  so  located  as  to  prevent  butts 
in  adjacent  strakes  coming  closer  together  than  two  frame 
spaces,  and  that  between  any  two  butts  in  the  same  frame 
space  there  are  five  "passing"  strakes,  or  strakes  having 
no  butt  in  that  particular  frame  space.  This  arrangement, 
or  "shift  of  butts,"  as  it  is  called,  is  for  the  purpose  of  pre- 
venting, as  much  as  possible,  lines  of  weakness,  since  any 
riveted  joint  is  weaker  than  the  plating  itself.  In  Fig. 
46  the  shift  of  butts  shown  gives  five  passing  strakes  and 
each  plate  is  six  frame  spaces  long.  If  the  plate  lengths 
were  different  a  different  shift  of  butts  would  have  to  be 
made.  The  lengths  of  the  plates  are  always  exact  multiples 
of  the  frame  spacing  (plus,  of  course,  the  width  of  the  butt 
lap,  if  the  butts  are  lapped)  in  order  to  keep  the  butt  joints 
clear  of  the  frames.  Various  combinations  of  plate-lengths 
and  numbers  of  passing  strakes  are  possible.  The  plates 
should  be  as  many  frame  spaces  long  as  possible  in  order  to 
obtain  a  good  shift  of  butts,  but  the  length  is  of  course 
limited  by  the  capacity  of  the  rolling  mills  to  produce 
long  plates,  so  that  in  ordinary  sized  ships  the  plates  are 
usually  between  20  and  30  feet  long. 

As  the  ship  becomes  fine  toward  the  ends,  and  the 
girths  of  the  frames  consequently  reduced,  in  order  to 
prevent  giving  an  excessive  taper  to  the  strakes  it  is  nec- 
essary to  drop  certain  of  them.  Such  strakes,  which  do  not 
run  for  the  full  length  from  stem  to  stern  or  stern  post,  are 
called  drop  strakes,  or  stealers.  The  last  plate  in  such  a 
strake  is  usually  triangular  in  shape,  and  one  of  the  adjacent 


112 


PRACTICAL  SHIP  PRODUCTION 


strakes  for  the  remainder  of  its  length  to  the  end  of  a  ship 
(in  the  case  of  lapped  seams)  becomes  both  an  inner  and 
outer  or  a  clinker  strake  instead  of  an  entirely  inner  strake, 
or  an  entirely  outer  strake.  See  sketch  of  a  stealer  in 
Fig.  50. 

Where  the  strakes  pass  over  water-tight  bulkheads— 
which  take  the  places  of  certain  frames  and  have  more 
closely  spaced  riveting — bulkhead  liners  are  usually  fitted  to 
compensate  for  the  excessive  weakening  caused  by  the 
greater  number  of  rivet  holes.  Figure  51  shows  one  form  of 
bulkhead  liner,  the  outer  strake  being  reinforced  by  the 


FIG.  50. — Stealer. 

diamond  shaped  doubling  of  the  liner.  When  a  butt  occurs 
between  a  bulkhead  and  the  adjacent  frame  on  either  side  of 
the  bulkhead,  the  bulkhead  liner  is  extended  on  that  side  to 
form  a  strap  for  the  butt,  the  two  plates  then  being  butted 
instead  of  lapped.  Longitudinal  brackets  connecting  the 
outer  strakes  to  the  bulkheads  are  sometimes  used  instead 
of  bulkheads  liners,  these  being  commonly  fitted  on 
stringers. 

The  shell  plating  terminates,  at  the  ends  of  the  ship,  in 
the  stem,  the  stern  post  or  frame,  propeller  brackets, 
etc.  It  is  made  especially  thick  at  these  places  or  is  doubled 
and  secured  by  heavy  rivets  which  should  be  very  carefully 
driven.  The  plating  is  also  doubled  or  reinforced  at  the 


STRUCTURAL  MEMBERS  OF  SHIPS 


113 


•Liner 


Bounding  Bar 
Outer  Strake 


bows,  in  the  vicinity  at  which  it  might  be  dented  in  by  the 
anchors  or  by  ice  or  other  floating  objects,  and  also  around 
openings  cut  in  the  shell  for  various  fittings,  tubes,  etc. 
The  gar  board  and  sheer  strakes  are  made  of  extra  thick 
plating  in  order  to  give  longitudinal  or  girder  strength 
to  the  ship.  Usually  the  bilge  strake  is  also  made  a  trifle 
heavier  than  the  remainder  of  the  plating.  Except  for 
local  stiffenings,  all  strakes 
have  lighter  plating  near  the 
ends  of  the  ship  than  amid- 
ships. 

The  inner  bottom  plating 
is  composed  of  rectangular 
shaped  plates  disposed  in  a 
manner  quite  similar  to  those 
of  the  outer  shell.  The 
strakes  are  continuous  longi- 
tudinally so  that  the  inner 
bottom  furnishes  consider- 
able additional  girder 
strength  to  the  ship.  The 
centre  strake,  attached  to  FIG.  51.— Bulkhead  liner, 

the  top  of  the  centre  vertical 

keel,  is  usually  made  extra  heavy  and  serves  in  reinforcing 
the  heavy  centre  line  girder  over  the  keel.  It  is  sometimes 
called  the  rider  plate.  The  lengths  of  the  inner  bottom 
plates  are  commonly  the  same  as  those  of  the  shell  and  a 
similar  shift  of  butts  is  obtained.  The  thickness  of  the 
plates  is  less  than  for  those  of  the  outer  shell.  The  seams 
of  inner  bottom  plating  are  often  joggled.  Seams  are 
always  kept  clear  of  longitudinals. 

In  merchant  vessels  the  outer  flat  strake  of  the  inner 
bottom  plating  is  ordinarily  connected  to  the  shell  plating 
by  means  of  a  flanged  strake  set  normally  to  the  shell 
plating,  called  the  margin  plate.  The  arrangement  of  the 
inner  bottom  plating  is  shown  in  Figs.  31,  32,  33  and  34. 
In  war  ships  (and  some  merchant  ships)  the  inner  bottom 


114 


PRACTICAL  SHIP  PRODUCTION 


extends  completely  up  to  the  first  deck  above  the  normal 
water  line. 

4.  DECKS 

Decks  are  ordinarily  curved  surfaces,  having  a  longitu- 
dinal sheer  and  an  athwartships  camber,  and  are  bounded 
by  the  sides  of  the  ship  and  by  the  edges  of  trunks,  hatches, 
etc.,  cut  through  them.  The  deck  plating  or  planking  is 
somewhat  similar  to  the  shell  plating  or  planking  and  is 
supported  at  regular  intervals  by  beams.  The  beams  are 
supported  at  their  outboard  ends  by  the  frames  to  which 
they  are  attached  by  beam  knees  or  brackets  and  at  inter- 
mediate points  by  pillars,  stanchions,  and  bulkheads. 


-Frame 


WELDED 
BEAM   KNEE 


BEAM  BRACKET 
FIG.  52. — Connections  of  deck  beams  to  frames. 


Deck  beams  are  usually  deep  channels  or  bulb  angles 
(although  other  shapes  are  sometimes  employed)  and  are 
bent  slightly  to  the  proper  camber.  The  methods  of 
attaching  the  beams  to  the  frames  are  illustrated  in  Fig.  52. 
A  beam  knee  is  formed  by  splitting  the  end  of  the  beam  and 
bending  the  two  parts  to  the  shapes  shown,  a  piece  being 
then  welded  in  to  complete  the  knee.  A  less  expensive 
construction,  but  a  heavier  one  is  the  bracket,  which  is  a 
simple  triangular  plate  fitted  between  the  frame  and  beam, 
often  flanged  on  the  sloping  edge  as  shown. 

Where  openings  must  be  cut  in  decks  cartings  or  fore  and 
aft  beams  are  fitted  and  the  beams  or  "half  "  beams  extend 
up  to  and  are  secured  to  the  carlings.  The  carlings  are 


STRUCTURAL  MEMBERS  OF  SHIPS 


115 


terminated  at  the  beams  as  shown  in  the  lower  sketch  in 
Fig.  53,  and  the  general  arrangement  it  shown  by  the  upper 
sketch  in  the  same  figure.  Usually  a  vertical  boundary  of 
plating  is  fitted  around  the  hatch  opening  called  a  coaming. 
In  this  case  the  coaming  plate  would  replace  the  right-hand 
clip  shown  in  Fig.  53. 

Deck  Plating  and  Planking. — The  upper  edges  of  the 
deck  beams  are  covered  over  with  plating  or  planking  or 
both.  The  upper  strength  deck  or  main  deck  is  usually 
completely  covered  with  steel  plating,  made  heavier  than 


"Half" 
Beams 


Carlings 

Sides  of  ship 


Beams 


PLAN  OF  DECK  WITH  PLATING  REMOVED 


Clip 


Beam 
'Carling 

FIG.  53. — Deck  beams  and  carlings. 

the  other  decks  for  purposes  of  strength.  The  outboard 
strake  of  this  plating  which  connects  with  the  shell  plating 
is  called  the  deck  stringer  plate  and  is  made  especially  heavy. 
It  is  connected  by  a  heavy  angle  bar  to  the  sheer  strake  of 
the  shell  plating  and  acts  with  it  in  furnishing  upper  flange 
strength  to  the  ship  as  a  girder.  The  deck  stringer  is 
fitted  in  every  case  whether  the  remainder  of  the  deck  is  to 
be  plated  or  merely  planked.  Its  inner  edge  runs  approxi- 
mately parallel  to  its  outer  edge. 


116 


PRACTICAL  SHIP  PRODUCTION 


The  remainder  of  the  deck  plating  is  arranged  in  strakes 
parallel  to  the  centre  line  of  the  ship.  The  seams  are 
commonly  joggled  except  in  cases  where  the  projecting 
laps  would  be  objectionable,  as  for  a  deck  to  be  covered 
with  linoleum  or  protective  deck  plating,  in  which  cases  the 
deck  plating  is  worked  flush  with  butt  and  seam  straps 
underneath. 


Bracket 


ANGLE 
FRAMES 


"Shell  Plating 


^Vood  Deck  Planking 

Stringer  Anglej 
Waterway  Angle 


Half  Round  Beading 
Sheer  Strake 
Bracket 

"Frame 

~    U         \\ 

\          J^** 

Beam\    \/^^* 

SECTION  THROUGH  SIDE 
OF  MAIN  DECK 

FIG.  54. — Connections  at  sides  of  watertight  decks. 

The  boundaries  of  the  deck  plating  are  connected  to  the 
intersecting  coamings,  shell  plating  or  bulkheads  by  bound- 
ing or  boundary  bars  or  simple  angles  one  flange  of  which  is 
riveted  to  the  deck  plating  and  the  other  to  the  coaming, 
shell  plating  or  bulkhead,  as  the  case  may  be. 

Methods  of  connecting  the  deck  plating  of  a  water-tight 


STRUCTURAL  MEMBERS  OF  SHIPS 


117 


deck  to  the  shell  plating  are  shown  in  the  three  upper 
sketches  of  Fig.  54.  The  stringer  plate  is  notched  out 
around  each  frame  and  forged  angle  staples  are  fitted 
between  and  around  the  frame  bars.  Typical  constructions 
for  angle,  Z-bar  and  channel  frames  are  shown,  but  numer- 
ous other  arrangements  are  possible  and  will  be  found  used 
to  accomplish  the  same  purpose — which  is  to  furnish  a 
means  of  making  a  completely  water-tight  connection  of 
deck  to  shell. 

In  the  case  of  the  highest  deck  of  the  hull  such  stapling 
is  not  necessary  as  the  frames  terminate  below  the  deck. 
Here  the  stringer  angle  bar  runs  continuously  along  the 
inner  surface  of  the  top  of  the  sheer  strake  and  outboard 


Yellow  Pine  Plank 
3  to  3%"thick. 


J.  Thread,  Cotton 

V      3  Threads,  Oakum 

\\   Jeanne  Glue 

\      \ 


Wood  plug,  set  in 
White  Lead 


Grommet 


Square  Neck 


Galvanized 
Iron  Bolt 


Deck  Plating 


Grommet 


Deck  Beam 
FIG.  55.  —  Butt  of  deck  planking  over  steel  deck. 

upper  surface  of  the  deck  stringer  plate,  as  shown  in  the 
lowest  sketch  of  Fig.  54.  Another  angle  is  usually  run 
parallel  to  the  stringer  angle  to  form  a  waterway  along 
the  edge  of  the  deck,  and  to  form  the  outer  boundary  of 
the  wood  planking,  as  shown. 

The  wood  for  deck  planking  is  ordinarily  yellow  pine  or 
teak.  The  planks  are  generally  of  square  section  and  about 
3"  or  3K"  on  a  side  if  of  yellow  pine,  and  of  nearly  the 
same  thickness  but  8"  or  10"  wide,  if  of  teak.  The  planks 
are  commonly  run  straight  and  fore  and  aft  except  at 
curved  boundaries  where  specially  shaped  margin  planks 
are  fitted,  notched  to  take  the  ends  of  the  straight  planks, 


118  PRACTICAL  SHIP  PRODUCTION 

They  are  secured  to  the  steel  plating  underneath  by  means 
of  galvanized  iron  bolts  (usually  about  %"  in  diameter) 
as  shown  in  Fig.  55.  If  a  complete  steel  deck  is  not  fitted 
the  bolts  are  run  through  the  upper  flanges  of  the  steel 
deck  beams,  or  through  small  steel  plates  riveted  to  those 
flanges.  Both  the  seams  and  butts  of  the  planking  are 
so  formed  as  to  have  a  section  similar  to  the  butt  shown  in 
Fig.  55,  and  are  made  water-tight  by  being  calked  with 
cotton  and  oakum  driven  securely  in  and  covered  with 
about  y±J  of  marine  glue  or  pitch.  Sometimes,  as  in  the 
case  of  yachts,  putty  is  used.  Lampwick  grommets 
soaked  in  white  lead  are  fitted  under  the  heads  of  the 
bolts  and  between  the  steel  deck  and  washers  above  the 
nuts.  Round  plugs  with  the  grain  running  the  same  as 
that  of  the  planking  are  driven  in  to  close  the  holes  over  the 
heads  of  the  bolts. 

When  a  complete  steel  deck  is  not  fitted  there  are  often 
fitted  under  the  wood  planking,  and  in  addition  to  the 
stringer  plates  certain  narrow  strips  of  plating  running 
diagonally  to  help  tie  the  beams  together  and  reinforce 
the  deck.  Also  there  are  sometimes  one  or  more  inboard 
strakes  of  plating  at  or  near  the  centre  line  running 
longitudinally. 

In  order  to  reinforce  the  deck  beams  and  relieve  the 
brackets  and  side  frames  of  the  total  load  of  the  deck 
vertical  stanchions  or  pillars  are  usually  fitted  between  decks. 
These  are  of  various  sizes  and  constructions,  some  being 
of  simple  round  section,  solid  or  hollow,  and  some  being 
built  up  of  various  plates  and  shapes  riveted  together. 

A  form  often  used,  the  pipe  stanchion,  consists  of  a 
wrought  steel  or  iron  tube,  fitted  at  its  upper  end,  or  head, 
and  lower  end,  or  heel,  with  special  pieces  for  securing  it  in 
place.  Such  a  stanchion  is  shown  in  Fig.  56. 

Stanchions  should  be  located  in  vertical  lines,  one  above 
the  other,  between  successive  decks,  so  that  the  forces 
will  be  transmitted  directly  through  them  to  the  bottom 
of  the  ship.  They  may  be  closely  or  widely  spaced,  but 
owing  to  the  room  that  they  take  up  and  the  interference 


STRUCTURAL  MEMBERS  OF  SHIPS 


119 


that  they  cause  in  holds  and  other  compartments  it  is 
frequently  desirable  to  have  them  widely  spaced. 

When  stanchions  are  widely  spaced  instead  of  being 
attached  directly  to  the  beams  over  them  longitudinal 
deck  girders  are  fitted  underneath  the  decks  and  the  stan- 
chions are  attached  to  these  girders.  The  simplest  form  of 
girder  is  a  single  angle  bar  running  along  the  lower  edge 
of  the  deck  beams  as  shown  in  the  left  sketch  of  Fig. 


HEAD 


Deck  Plating  — 

^~ 

x 

Deck  Beam 

iJTr<¥ 

- 

| 

C° 

2)J 

\ 

!' 

^v 

r            <£§[ 

r 

Pine  Stanchion  - 

i 
i 

jr 

1 
1 
i 

*"  \ 

1 
1 

1  —  -J 
** 

1        _^ 

j 

HEEL 


Pipe  Stanchion 


Forged  Heel 


FIG.  56.— Stanchion. 

57.  If  the  beam  has  a  lower  flange  the  girder  is  riveted 
to  this  flange.  If  not,  a  short  clip  is  fitted  on  each  beam  in 
way  of  the  girder,  as  shown  in  the  sketch  for  this  purpose. 
The  load  of  the  deck  between  stanchions  is  transmitted 
to  the  stanchions  through  the  girders. 

Many  different  types  of  deck  girders  are  in  use,  some  com- 
paratively simple,  like  the  one  just  described  and  others 
of  various  more  or  less  elaborate  construction.  Where; 


120  PRACTICAL  SHIP  PRODUCTION 

the  number  of  stanchions  must  be  greatly  reduced,  or 
stanchions  done  away  with  entirely,  very  deep  girders, 
built  up  of  plates  and  angles  and  reinforced  by  athwartship 
brackets  similar  to  the  one  shown  in  the  right  sketch  of 
Fig.  57  are  fitted.  In  this  type  it  will  be  noted  that  the 
girder  consists  of  a  continuous  deep  plate  with  continuous 
lower  angles  and  plate  below.  The  construction  is  similar 
to  that  of  keelsons,  and  stringers. 

In  certain  compartments  the  steel  deck  plating  is  covered 
with  linoleum  which  is  secured  to  it  by  a  special  cement. 
Other  spaces  have  cement  and  tiling  (bath  rooms,  etc.) 
over  the  steel  plating,  or  other  special  deck  coverings. 


££lt>      „       |  DeckBeam- 

3iip 

, .   ,  /\.^  4  II  .^-  Girder  Plate 

'irder  Intercostal  Clip/        X         fVT        (notched  at 

/  \y\  Deck  Beams) 

Flanged  Bracket  / 

/       ^Mt-y—  Continuous  Girder 
Clip/  Angles 


Stanchion— M 


Continuous  Plate 
SINGLE  ANGLE  GIRDER 

"Stanchion 
DEEP  PLATE  ANGLE 
FIG.  57. — Deck  girders. 

Decks  are  ordinarily  made  water-tight  in  order  to  increase 
the  danger  of  loss  of  buoyancy  caused  by  damage  to  the 
shell  plating.  Therefore  as  a  general  rule  all  openings  cut 
in  decks  should  have  means  for  their  being  tightly  closed. 
Some  of  the  methods  used  for  this  purpose  are  shown  in  Fig. 
58.  The  simplest  is  a  flat  plate  secured  by  means  of  stud 
bolts  as  shown  in  the  upper  sketch.  A  gasket  of  canvas 
soaked  in  red  lead  or  some  other  suitable  material  is 
interposed  between  the  cover  and  the  deck  plating.  If 
the  joint  must  be  oil- tight  canvas  soaked  in  a  mixture  of 
pine  tar  and  shellac  or  card  board  and  varnish  is  used  for 
the  gasket.  Another  method,  used  for  covers  to  manholes 
(small  oval  holes  just  big  enough  to  admit  a  man)  is  shown 
in  the  middle  sketch.  Here  a  heavy  strong  back  .and  a 
large  bolt  through  the  centre  of  the  manhole  plate  are 


STRUCTURAL  MEMBERS  OF  SHIPS 


121 


used.  Where  perfect  water-tightness  combined  with  quick 
removal  is  required,  some  method  similar  to  that  shown 
in  the  lowest  sketch  must  be  used.  Here  a  rubber  gasket 
held  by  strips  is  secured  around  the  outer  edge  of  the  cover 
plate,  so  that  when  the  plate  is  drawn  down,  by  bolts 
fitted  as  shown,  the  gasket  is  compressed  against  the  upper 


Bolted  Plate 


BOLTED  PLATE 


Strongback 


STRONGBACK 
AND  BOLT 


Manhole  Plate  (oval) 


Do* 


Hatch  Cover 


Bolt 


WATERTIGHT 
HATCH  COVER 


Coaming  Ang 


Deck  Plating 


FIG.  58. — Covers  for  openings  in  watertight  decks. 

edge  of  the  coaming.  This  general  method  is  used  con- 
siderably for  manhole  covers,  hatch  covers,  water-tight 
doors,  etc.  The  circumferences  of  such  openings  or  of 
their  covers  may  be  reinforced  by  stiffening  rings. 

6.  BULKHEADS 

Bulkheads  are  vertical  diaphragms  or  partitions  of  vari- 
ous construction.  According  to  the  directions  in  which 
they  extend  they  are  called  transverse  or  longitudinal. 


122  PRACTICAL  SHIP  PRODUCTION 

Longitudinal  bulkheads  are  not  much  used  in  merchant 
ships,  which  usually  require  broad  hold  spaces,  but  are  im- 
portant features  in  warships  wrhere  they  serve  to  increase 
the  fore  and  aft  strength,  and  underwater  protection. 

Transverse  bulkheads  are  important  in  all  types  of  ships 
since,  as  well  as  furnishing  transverse  strength  by  their 
stiff  diaphragm  action  and  the  support  that  they  give  to 
stringers,  decks,  etc.,  they  subdivide  the  length  of  the  ship 
into  a  number  of  holds  or  compartments  and  thus  limit 
the  space  that  may  be  flooded  if  the  shell  plating  is  punc- 
tured. In  fact  it  may  be  said  that  the  chief  function  of 
all  such  bulkheads,  except  those  not  forming  an  integral 
portion  of  the  hull  structure,  is  to  furnish  a  means  of  water- 
tight subdivision. 

Bulkheads,  like  decks,  consist  of  plating  and  reinforcing 
bars.  In  the  case  of  bulkheads  the  reinforcing  bars  are 
called  bulkhead  stiff eners.  In  some  cases  the  stiff eners 
are  formed  by  flanging  the  edges  of  the  bulkhead  plates, 
but  the  principle  is  the  same.  In  some  cases  the  stiff  eners 
are  fitted  in  horizontal  lines  only,  sometimes  in  vertical 
lines  only,  and  in  some  cases  both  horizontal  and  vertical 
stiff  eners  are  used  on  the  same  bulkhead. 

A  bulkhead  designed  to  assist  in  watertight  subdivi- 
sion must  be  made  of  heavy  enough  plating  and  must  be 
sufficiently  stiffened  to  resist  bending  or  bulging  in  case  of 
flooding  of  either  of  the  compartments  of  which  it  forms  a 
boundary.  If  the  sightest  deflection  takes  place  some  of  the 
rivets  or  seams  are  almost  sure  to  start  leaking.  There- 
fore the  stiffeners  must  be  strong,  closely  spaced,  and 
properly  supported  at  their  ends.  In  very  large,  deep  bulk- 
heads the  construction  must  be  much  more  rugged  than  in 
small  ones,  depending,  as  it  does,  upon  the  head  of  water  to 
which  they  may  be  subjected. 

In  Fig.  59  is  shown  a  simple  construction  of  a  bulkhead. 
The  plating  is  arranged  in  horizontal  strakes  and  the  stiff- 
eners, in  this  case  bulb-angles,  run  vertically.  The  plating 
is  secured  to  the  deck,  shell,  and  tank  top  plating  by  means 
of  double  angles  called  boundary  or  bounding  bars.  The 


STRUCTURAL  MEMBERS  OF  SHIPS 


123 


lower  strakes  of  plating  (which  would  have  to  withstand 
greater  pressures)  are  made  heavier,  and  the  lower  ends 
of  the  stiffeners  are  given  a  rigid  support  by  means  of  plate 
brackets  riveted  to  their  fore  and  aft  flanges  and  to  clips 
which  are  in  turn  riveted  to  the  tank  top. 

The  above  described  construction  is  modified  and  ex- 
tended in  a  great  many  different  ways  to  suit  different  sizes 
and  types  of  ships.  In  some  cases  single  boundary  bars  are 


Deck  Plating 


Bounding 
Bars 


/Stiffener 

Bulkhead 
Plating 


.Brackets-^ 


/Bounding 
J      Bars 

MX/Bracket 

Tank  Top 


leBo 


torn 


Stiffeners 


SECTION  ON  AB 


Shell  Plating 


SECTION  ON  C  D 

FIG.  59.— Bulkhead. 

sufficient.  The  plating  is  sometimes  arranged  in  vertical 
strakes.  The  seams  are  frequently  joggled.  The  stiffeners 
may  be  simple  angle  bars,  channels,  Z-bars,  T-bars,  I-beams, 
or  may  be  built  up  of  plates  and  shapes  in  the  form  of  heavy 
girders  in  which  case  their  heads  and  heels  are  reinforced 
and  connected  to  the  decks  and  inner  bottom  by  large 
built  up  brackets  with  heavy  face  bars.  Ordinarily  the 
plating  of  the  decks  is  continuous  and  the  bulkhead  plating 


124  '  PRACTICAL  SHIP  PRODUCTION 

is  cut  at  the  decks,  although  this  may  not  always  be  the 
case,  especially  for  longitudinal  bulkheads. 

Transverse  bulkheads  designed  as  watertight  dia- 
phragms must  be  carefully  fitted  where  necessarily  pierced 
by  longitudinal  members,  such  as  stringers,  girders,  piping, 
etc.,  so  as  to  maintain  water  tightness.  To  this  end  staples 
and  collars  made  similarly  to  those  shown  in  Fig.  54  are 
fitted  around  the  longitudinal  members  at  the  bulkheads. 
The  same  applies  to  transverse  members  piercing  longi- 
tudinal watertight  bulkheads. 

Watertight  bulkheads  are  tested  by  filling  the  compart- 
ments of  which  they  form  boundaries  with  water,  and 
ascertaining  if  any  leaks  occur. 

Horizontal  bulkhead  stiff  en  ers  are  usually  arranged  so 
as  to  connect  with  side  and  hold  stringers,  where  such 
members  occur. 

Certain  non-watertight  or  partition  bulkheads  are  found 
in  all  ships,  being  installed  for  purposes  of  subdivision  of 
space  into  staterooms,  galleys,  pantries,  wash  rooms,  store- 
rooms, etc.,  etc.  These  may  be  of  wood,  light  sheet  metal 
or  wire  mesh,  and  furnish  little  if  any  strength  or  water- 
tightness.  Longitudinal  coal  bunker  bulkheads  in  mer- 
chant vessels  are  fairly  strong  and  heavy  but  are  not 
usually  made  watertight. 

Doors  in  water-tight  bulkheads  must  be  watertight  and 
are  usually  constructed  on  the  principle  shown  in  the  lowest 
sketch  of  Fig.  58,  the  details,  of  course,  being  somewhat 
different. 

6.  MISCELLANEOUS 

The  main  structural  members  of  ships  have  been  de- 
scribed in  the  preceding  sections  of  this  chapter,  but  there 
are,  in  addition,  certain  auxiliary  structures  and  fittings 
which  are  either  built  into  or  securely  attached  to  the  hull, 
and  with  which  the  shipbuilder  is  therefore  concerned.  Of 
these  there  are  a  great  number  and  their  design  and  con- 
struction vary  considerably.  Among  the  principal  ones 
may  be  mentioned  engine  and  boiler  foundations,  and 


STRUCTURAL  MEMBERS  OF  SHIPS 


125 


foundations  for  shaft  bearings,  thrust  blocks,  auxiliary 
machinery,  winches,  guns,  davits,  masts,  derricks,  etc., 
hawse  pipes,  chain  pipes,  mooring  pipes,  chocks,  bitts, 
rails  and  bulwarks,  bilge  and  docking  keels,  fenders,  etc. 
Engine  foundations  must  be  heavy  and  strongly  built  and 
well  supported  by  the  adjacent  structure  of  the  ship. 
Often  times  the  frame  spacing  is  reduced  and  the  floors  made 
deeper  under  the  engines  in  order  to  give  additional  vertical 
strength.  The  foundations  for  the  engines  are  built  up  on 
top  of  the  inner  bottom  usually  of  plates  and  angles  well 

ndation  Plate 

Bracket \/ 

Girder       / 
Plate 


Longitudinals^/  /Shell  Plating 

FIG.  60. — Portion  of  engine  foundation. 

bracketed  and  reinforced  in  all  directions.  A  typical 
construction  is  shown  in  Fig.  60.  The  girder  plates  of 
the  foundation  should  be  nearly  in  line  with  longitudinals 
so  as  to  preserve  continuity  of  strength  and  the  athwart- 
ship  members  are  ordinarily  directly  over  the  floors. 

A  typical  method  of  supporting  the  boilers  is  shown  in 
Fig.  61.  The  saddles  are  plates  cut  to  a  curved  shape  to 
fit  against  the  boiler  shell  and  are  reinforced  by  double 
angles  around  their  edges  as  shown,  and  the  successive 
saddles  are  connected  at  their  outer  sides  by  longitudinal 
plates. 

Special  foundations  of  a  great  many  different  types  are 
installed  in  other  parts  of  the  ship,  the  principles  of  con- 


126 


PRACTICAL  SHIP  PRODUCTION 


STRUCTURAL  MEMBERS  OF  SHIPS 


127 


struction   being   in   general  the  same  as  for  engine  and 
boiler  foundations. 

Hawse  pipes  are  large  castings,  usually  steel,  securely 
built  into  the  bows  of  the  ship,  through  which  the  anchor 
chains  may  pass  (see  sketch  of  hawsepipe  in  Fig.  62). 
Chain  pipes  serve  a  similar  purpose  but  lead  entirely  inside 
of  the  ship  and  nearly  vertically  down  to  the  chain  locker, 
as  they  do  not  have  to  have  the  peculiar  terminations  of 


Bolster 


Stiffener 


FIG.  62. — Hawse  pipe. 

hawse  pipes.  At  the  ends  of  either  a  hawse  pipe  or  chain 
pipe,  where  the  direction  of  the  chain  is  sharply  changed, 
the  edges  must  be  well  rounded  off  by  heavy  bolsters,  as 
shown  in  Fig.  62. 

For  leading  and  securing  hawsers  to  the  ship  from  a  dock 
or  tug  chocks,  bitts,  cleats,  and  similar  fittings  are  securely 
attached  to  the  decks,  especially  to  the  weather  deck. 
Figure  63  shows  bitts  and  a  chock  and  a  method  of  at- 


128 


PRACTICAL  SHIP  PRODUCTION 


taching  such  heavy  fittings,  which  must  transmit  heavy 
stresses  to  the  hull. 

In  Fig.  64  are  shown  a  section  of  a  rail  and  bulwarks,  two 
types  of  fenders,  a  docking  keel  and  two  types  of  bilge  keels. 
The  rail  and  bulwarks  form  a  fence  or  enclosure  around  the 
edge  of  an  open  deck.  The  plating  is  light  and  should  not 
be  considered  as  furnishing  much  strength  in  addition  to 


ELEVATION 


BITTS 


CHOCK 


PUN 


T?  TT 

LO     Sjv     oVv 


METHOD  OF  ATTACHMENT 
OF  BITTS  TO  DECK 


Plate 


FIG.  63. — Bitts  and  chock. 


that  of  the  sheer  strake.  In  many  cases  open  rails  are 
fitted  consisting  of  stanchions  and  horizontal  rods  with  a 
wood  railing  on  top.  Fenders  are  fitted  to  prevent  damage 
to  the  sides  of  tugs,  barges,  and  similar  vessels  which  fre- 
quently bump  against  other  vessels  or  against  docks. 
They  usually  run  along  the  sides  parallel  to  the  upper  deck 
and  a  few  feet  above  the  water  line.  Docking  keels  are 


STRUCTURAL  MEMBERS  OF  SHIPS 


129 


fitted  on  battleships  and  other  large  heavy  vessels  to  take  a 
portion  of  the  weight  when  in  dry-dock.  They  run  parallel 
to  the  centre  keel  and  are  usually  located  roughly  at  % 
of  the  half-beam  of  the  ship  out  from  the  centre  line. 
Bilge  keels  are  fitted  along  the  bilges  and  are  designed  to 
prevent  or  decrease  rolling.  They  are  sometimes  called 
rolling  chocks. 


Wood  Rail 


Brace 


Bulwark 
Plating 


Shell 
Plating 


Fender-^ 


Deck-Stringer 
Plate 

BULKWARKS  AND  RAIL 


*_  Shell 
Plating 


\t~Fender 


PLATE 
FENDER 


She! 
Plating 


Shell  Plating 


•Docking  Keel  Plate 

Teck  Filler 


Shell. 
Plating 


T-Bar  Bilge 

.Keel 
Built-up  Bilge  Keel1 

BILGE  KEELS 


DOCKING  KEEL 

FIG.  64. — Rail  bulwarks,  fenders,  docking  keel,  bilge  keels. 

Cofferdams  are  compartments  formed  by  placing  two  bulk- 
heads close  together,  the  space  between,  or  cofferdam,  being 
for  the  purpose  of  preventing  leaks  between  the  two  spaces 
on  either  side  of  the  cofferdam — as,  for  example,  between 
the  end  of  an  oil  tank  and  an  adjacent  compartment. 

Drainage  wells  are  small  pockets  placed  in  the  lowermost 
compartments  of  the  ship  (often  called,  in  this  connection, 
the  bilges)  in  order  to  permit  water,  etc.,  to  collect  therein, 
and  thus  to  be  readily  pumped  out. 


i      CHAPTER  IV 
DESIGN  OF  SHIPS 

1.  CONDITIONS  TO  BE  FULFILLED 

The  design  of  a  ship  is  the  first  step  in  the  process  of  ship 
production.  It  should  be  considered  broadly  as  a  question 
of  cause  and  effect.  A  ship  is  needed  to  fulfil  a  given 
purpose.  To  fulfil  this  purpose  she  must  meet  certain 
requirements.  In  meeting  these  requirements  certain 
obstacles  must  be  overcome.  The  design  of  a  ship  then 
resolves  itself  into  a  problem  of  fulfilling  the  requirements 
sought,  while  at  the  same  time  overcoming  the  obstacles 
that  are  bound  to  be  encountered.  The  designer  is  the 
planner  who  gives  the  orders,  which  must  be  executed  by 
the  shipbuilder.  Each  must  be  familiar,  to  a  certain 
extent,  with  the  problems  with  which  the  other  is  con- 
fronted in  order  that  they  may  work  together  harmoniously 
in  the  process  of  ship  production.  Their  work  is  also  closely 
related  to  the  questions  of  material,  tools  and  labor  avail- 
able. The  designer's  work  is  largely  theoretical  in  nature; 
the  shipbuilder's,  practical. 

If  the  ship  that  is  desired  is  to  fulfil  certain  special  and 
unusual  requirements,  the  designer's  task  becomes  more 
difficult,  while,  if,  on  the  other  hand,  the  requirements 
of  the  ship  are  practically  the  same  as  those  of  other  ships 
that  have  already  been  designed,  the  designer's  work  is 
correspondingly  reduced.  Many  shipyards  have  de- 
veloped certain  more  or  less  standard  designs  for  ships, 
which  they  have  built  over  and  over  again  to  the  same 
plans.  For  such  ships  the  designer's  task  disappears, 
the  problem  of  producing  them  being  entirely  one  for 
the  shipbuilder. 

At  the  present  time  the  great  need  in  ship  production  is 
quantity.  Any  ship  that  is  capable  of  carrying  cargo  or 

130 


DESIGN  OF  SHIPS  131 

men  across  the  ocean  is  very  valuable,  and  since  there  'are 
already  available  many  plans  for  ships  that  will  fulfil 
these  requirements,  the  need  is  now  more  for  shipbuilders 
than  for  ship  designers. 

The  space  devoted  to  a  discussion  of  the  design  of  ships 
will  therefore  be  limited,  in  order  that  more  consideration 
may  be  given  to  the  problems  met  with  in  the  building  of 
ships.  It  is,  however,  desirable  that  the  shipbuilder  be 
conversant,  in  a  general  way,  with  the  work  of  the  designer. 

The  problem  which  is  given  to  the  designer  for  solution 
is  to  produce  the  plans  and  specifications  for  a  ship  that 
will  have  a  certain  speed,  carrying  capacity,  steaming 
radius,  seaworthiness,  etc.  These  characteristics  vary 
greatly  with  the  type  of  ship.  For  example:  in  fighting 
ships  certain  armament  and  armor  must  be  carried; 
in  passenger  ships  a  certain  number  of  passengers  must 
be  fully  provided  for;  in  cargo  ships  a  certain  amount  of 
cubic  space  and  weight  carrying  capacity  must  be  provided. 
The  problem  is  often  complicated  by  the  question  of  cost. 
A  limit  in  cost  naturally  causes  a  limit  in  size,  and  certain 
characteristics  can  be  obtained  only  by  an  increase  in  size. 
The  design  of  a  ship  is  therefore,  in  many  cases,  in  the  nature 
of  a  compromise.  Certain  qualities  must  be  sacrificed  in 
order  to  obtain  certain  others.  The  ideal  case  is  that  in 
which  the  designer  is  simply  given  the  conditions  to  fulfil, 
without  any  limitation  as  to  the  size  of  the  ship.  Under 
such  conditions  he  can  produce  the  best  results. 

Except  in  very  unusual  cases,  the  design  of  a  ship  is  based 
upon  other  ships  already  built  and  known  to  be  satisfactory. 
The  process  of  design  consists  in  adapting  data  already  at 
hand  to  suit  the  needs  of  the  particular  ship  being  designed. 
For  this  reason  it  is  very  important  for  the  designer  to 
possess  as  many  different  plans  and  as  much  data  of  all 
kinds  regarding  various  ships  already  built  as  possible. 
This  statement  is  based  upon  the  well-known  fact  that 
experience  is  a  better  guide  than  theory.  Nevertheless, 
it  must  not  be  forgotten  that  without  theory  and  in- 
ventiveness, very  little  progress  could  ever  be  made. 


132  PRACTICAL  SHIP  PRODUCTION 

2.  CHOICE  OF  PRINCIPAL  ELEMENTS 

Having,  been  given  the  various  requirements  that  are 
to  be  fulfilled  in  the  proposed  ship,  the  designer,  taking 
advantage  of  his  knowledge  and  experience,  and  of  the 
data  that  he  has  available,  determines  roughly  upon  the 
size,  or  displacement,  of  the  ship.  Then,  having  due 
regard  for  the  conditions  to  be  met,  he  selects  roughly  the 
principal  dimensions  and  coefficients — such  as  length, 
beam,  draft,  block  coefficient  of  fineness,  coefficient  of 
fineness  of  midship  section,  and  load  water  line  coefficient. 
This  is  largely  a  tentative  process,  since  these  elements 
are  more  or  less  inter-related,  and  is  usually  determined 
fairly  well  by  the  designer's  knowledge  of  previous  ships. 
If  the  ship  is  very  similar  to  another  already  designed, 
a  number  of  these  elements  may  be  practically  fixed  in 
advance.  For  example  the  block  coefficient  of  certain 
types  of  ships  is  fairly  well  known,  as  are  the  ordinary  ratios 
of  length  to  beam  and  beam  to  draft.  Since  the  displace- 
ment is  directly  dependent  upon  the  product  of  length 
times  beam  times  draft  times  the  block  coefficient,  if  the 
displacement  has  been  decided  upon,  the  other  values  can 
be  fairly  readily  determined. 

The  earliest  rough  design  may  be  divided  into  two  parts : 

(1)  The  determination  of  the  principal  elements  of  form 
and  weight,  and 

(2)  The  drawing  of  the  lines  and  the  location  of  the 
various  weights  so  as  to  conform  to  the  elements  selected. 

The  principal  elements  of  form  are  the  length,  beam, 
draft  and  freeboard  and  the  various  coefficients.  The 
principal  elements  of  weight  may  be  roughly  expressed  as 
the  weight  of  the  hull,  fittings,  crew,  outfit,  etc.,  the 
weight  of  the  propelling  apparatus  (engines,  boilers,  aux- 
iliaries, etc.),  and  the  weights  that  are  consumable  or 
removable.  The  classifications  of  these  weights  are  very 
elastic  and  depend  upon  the  type  of  ship.  For  instance, 
in  war  ships  the  removable  weights  form  a  relatively  small 
percentage  of  the  displacement,  because  of  the  large  amount 


DESIGN  OF  SHIPS  133 

of  weight  required  to  be  permanently  carried,  for  military 
reasons,  made  up  of  armor,  turrets,  barbettes,  guns, 
torpedoes  and  the  mechanism  required  for  the  operation  of 
the  ship  and  her  weapons  of  offense,  while  in  most  merchant 
ships  a  great  proportion  of  the  displacement  is  given 
over  to  cargo  carrying  capacity. 

3.  CONSTRUCTION  OF  LINES  AND  DISTRIBUTION  OF  WEIGHTS 

Having  decided  tentatively  upon  the  principal  elements 
of  form  the  designer  proceeds  with  the  drawing  of  the 
lines.  After  the  lines  are  completed  the  various  "  weight 
groups  "  are  located  so  as  to  give  a  satisfactory  arrangement, 
practically,  and  at  the  same  time  to  fulfil  the  fundamental 
laws  governing  the  operation  of  all  ships.  These  "  weight 
groups "  consist  of  the  weight  of  the  hull  and  fittings, 
weight  of  engines,  boilers  and  auxiliaries,  weight  of  fuel 
and  water,  weight  of  officers,  crew,  and  their  effects,  and  a 
number  of  other  weight  groups  depending  both  upon  the 
type  of  ship,  and  the  method  of  grouping. 

Some  of  the  fundamental  laws  which  must  be  fulfilled 
are  briefly  outlined  below: 

(1)  The  sum  of  all  the  weight  groups  for  the  condition 
of  loading  assumed  in  the  design  must  be  equal  to  the 
weight  of  water  displaced  by  the  ship  at  the  design  draft. 

(2)  The  position  of  the  centre  of  gravity  of  the  combined 
total  of  all  the  weight  groups  must  be  in  a  vertical  line 
with  the  centre  of  buoyancy,  or  centre  of  figure  of  the 
under  water  volume  of  the  ship. 

(3)  The  vertical  position  of  the  centre  of  gravity  of  the 
combined  total  of  all  the  weight  groups  must  be  far  enough 
below  the  metacentre  to  give  a  suitable  metacentric  height, 
and  sufficient  righting  arm  for  all  angles  of  inclination  to 
which  the  vessel  may  ever  be  expected  to  heel. 

Preliminary  rough  calculations  of  the  positions  of  the 
centres  of  gravity  and  buoyancy,  and  of  the  metacentre, 
must  of  course  be  made  for  this  purpose.  A  certain  amount 
of  adjustment  is  usually  necessary  in  this  process,  since 


134  PRACTICAL  SHIP  PRODUCTION 

so  many  different  conditions  must  be  met  that  the  problem 
cannot  be  approached  in  a  strictly  mathematical  manner. 
Various  locations  must  be  assumed  for  the  centres  of  gravity 
of  the  main  weight  groups,  such  as  engines,  boilers,  fuel, 
cargo,  etc.,  and  the  amounts  of  these  weights  must  be 
estimated  on  the  basis  of  the  speed,  endurance,  cargo 
carrying  capacity,  etc.,  that  it  is  desired  to  give  to  the 
ship.  The  methods  of  making  the  calculations  are 
described  in  Section  5,  below. 

4.  PRINCIPAL  PLANS 

When  the  weights  have  finally  been  located  so  as  to  give, 
roughly,  the  desired  solution  of  the  problem,  the  next  step 
in  the  design  is  the  preparation  of  the  principal  plans 
which  show  in  detail  the  locations  and  weights  of  the  various 
members,  parts,  fittings  and  subdivisions  of  the  ship,  and 
from  which  exact  calculations  of  all  the  weights  of  the  ship 
may  be  made. 

The  principal  ones  of  these  plans  are,  usually,  the 
following : 

Midship  section  plan. 

Shell  expansion. 

Stem,  sternpost,  propeller  struts,  rudder,  etc. 

Engines,  boilers  and  auxiliaries,  etc. 

Inboard  profile. 

Outboard  profile. 

Deck,  hold  and  inner  bottom  plans. 

Cross  sections. 

Bulkhead,  deck,  and  inner  bottom  plating  plans. 

Various  piping  plans. 

The  midship  section  is  a  plan  showing  a  transverse  section 
of  the  ship  at  the  dead  flat  (similar  to  Fig.  28)  and  giving  the 
principal  dimensions  (or  scantlings)  of  the  various  shapes 
entering  into  the  construction  of  the  frames,  beams,  longi- 
tudinal, stringers,  etc.,  and  of  deck  and  shell  plating,  etc. 

The  shell  expansion  is  a  plan  showing,  in  detail,  the  sizes 
of  all  the  plates  forming  the  shell.  It  is  drawn  by  laying 
off  along  the  ship's  length  as  a  base,  ordinates  representing 


DESIGN  OF  SHIPS  135 

the  actual  girths  of  all  the  frames  together  with  their 
intersections  with  the  edges  of  the  various  shell  plates 
(or  the  landing  edges,  as  they  are  called).  It  will  be  noted 
that  this  is  an  expansion  in  the  transverse  direction  only, 
and  does  not  give  the  true  form  of  the  shell  plates.  A 
true  expansion  of  the  ship's  outer  form  cannot  be  drawn, 
since  it  is  an  undevelopable  surface.  In  order  to  obtain 
the  true  shapes  of  the  various  shell  plates  a  wooden  model 
is  made  and  the  plating  laid  off  thereon. 

Plans  of  the  stem,  sternpost,  propeller  struts,  rudder,  etc., 
are  simply  working  drawings  of  these  various  parts. 

Plans  of  the  engines,  boilers  and  auxiliaries,  etc.,  represent 
a  large  amount  of  investigation  and  calculation  on  account 
of  their  intricate  nature,  and  in  most  establishments  are 
prepared  by  a  set  of  designers  and  draftsmen  distinct  and 
separate  from  the  hull  designers,  and  forming  the  marine 
engineering  department. 

The  inboard  profile  is  a  plan  showing  a  longitudinal 
vertical  section  of  the  ship*  taken  through  the  centre  line 
(see  Fig.  18). 

The  outboard  profile  is  a  side  elevation  of  the  ship  showing 
the  masts,  rigging,  boats,  davits,  and  other  outer  fittings. 

Deck,  hold  and  inner  bottom  plans  are  views  of  the  various 
decks,  the  hold,  and  inner  bottom  as  seen  from  above,  and 
show  the  subdivision  of  these  various  spaces. 

Cross  sections  are  plans  showing  transverse  sections  of 
the  ship  at  various  points  along  her  length.  They  indicate 
special  features  of  framing,  subdivision,  etc.,  in  these 
localities. 

Bulkhead,  deck  and  inner  bottom  plating  plans  show  the 
details  of  plating,  riveting,  stiffening,  etc.,  of  the  various 
bulkheads  and  decks,  and  of  the  inner  bottom. 

Piping  plans  show  the  various  systems  of  drainage,  fire 
protection,  flushing,  plumbing,  fresh  water  supply,  ventila- 
tion, etc. 

In  addition  to  the  above,  in  the  case  of  war  ships,  there 
are  drawn  plans  of  the  armor,  guns,  gun  foundations, 
turrets,  barbettes,  torpedo  tubes,  etc. 


136  PRACTICAL  SHIP  PRODUCTION 

Also  there  must  be  plans  drawn  for  special  local  weights 
such  as  boats,  davits,  windlasses,  steering  gear,  anchors, 
winches,  dynamos,  etc.,  etc.,  unless,  as  is  often  the  case, 
plans  for  these  already  exist. 

In  preparing  the  principal  plans  the  designer  is  guided, 
in  the  case  of  merchant  vessels,  by  the  published  rules  of 
the  classification  society  under  which  the  ship  is  to  be  built. 
These  rules  provide  for  certain  scantlings  to  be  used  for 
each  size  of  ship,  so  that  the  designer,  having  decided  upon 
the  length,  beam,  depth,  and  principal  coefficients  of  his 
ship,  can,  by  referring  to  the  classification  society's  rules 
and  tables,  determine  at  once  the  proper  sizes  for  all  the 
principal  structural  members. 

The  warship  designer  is  not  limited  by  Lloyd's  or  any 
other  such  rules,  and  has  more  freedom  in  the  choice  of  the 
scantlings.  He  is  guided  principally  by  his  available 
information  regarding  other  ships  of  similar  type  and  size 
already  'built,  and  if  any  radical  departure  from  these  is 
made  very  careful  investigations  and  extensive  calculations 
are  necessary. 

6.  FINAL  CALCULATIONS 

Having  completed  the  principal  plans  the  next  step  of  the 
designer  is  the  detailed  weight  calculation.  The  principle 
involved  in  this  process  is  simple,  it  being  merely  the  deter- 
mination of  the  weight  of  each  part  and  the  exact  location 
of  its  centre  of  gravity,  and  the  combining  of  these  in 
groups,  so  as  eventually  to  determine  the  total  weight  of 
the  entire  ship,  and  the  position  of  its  centre  of  gravity. 
The  work  required  is,  however,  very  tedious,  and  involves 
an  enormous  amount  of  calculation,  on  account  of  the 
great  number  of  different  parts  to  be  considered  and  the 
irregular  shapes  of  many  of  them.  No  attempt  will  be 
made  here  to  describe  in  detail  the  methods  by  which  these 
calculations  are  made. 

In  conjunction  with  the  calculations  for  weights,  calcu- 
lations must  also  be  made  for  buoyancy,  stability  and  trim. 
These  also  are  simple  in  principle  but  tedious  and  involved 


DESIGN  OF  SHIPS 


137 


in  practical  application.  They  are  based  upon  the  general 
laws  discussed  in  Chapter  I. 

The  calculation  of  the  displacement  consists  in  finding  the 
total  volume  of  the  under  water  portion  of  the  ship  in 
cubic  feet.  This,  divided  by  35,  is  the  displacement  of  the 
ship  in  tons — since  a  ton  of  sea  water  occupies  35  cubic  feet. 

The  calculation  of  the  position  of  the  centre  of  buoyancy 
consists  in  finding  the  location  of  the  centre  of  figure  of  the 
under  water  portion  of  the  ship. 


BM  = 


FIG.  65.— Value  of  BM 

The  calculation  of  the  metacentric  height  is  briefly  as 
follows:  The  value  of  BM,  the  distance  of  the  metacentre 
above  the  centre  of  buoyancy,  calculated  after  the  position 
of  the  centre  of  buoyancy  B  has  been  calculated,  gives  the 
location  of  the  metacentre.  This,  together  with  the  loca- 
tion of  the  centre  of  gravity  G,  calculated  as  described 
above,  gives  a  means  of  finding  GM,  the  metacentric 
height. 

The  method  of  calculating  BM  is  based  upon  the  following 
general  principle: 

Let  Fig.  65  represent  the  cross  section  of  a  ship  inclined 


138  PRACTICAL  SHIP  PRODUCTION 

to  a  small  angle  A0.  Let  B  be  the  original  centre  of  buoy- 
ancy and  Bf  the  centre  of  buoyancy  as  inclined.  Let 
y  be  the  half  -beam  of  the  ship  at  this  section  and  let  longi- 
tudinal distances  be  represented  by  the  variable,  x.  Let 
the  volume  of  displacement  =  V. 

Since  A0  is  small  BBr  =  BM  -A0.  Also  the  moment  of 
the  new  volume  of  displacement  about  the  plane  passed 
longitudinally  through  OB  is  T$B'  V. 

But  since  this  new  volume  of  displacement  has  been 
formed  by  subtracting  the  wedge,  of  which  WOW  is  a 
section,  from  the  original  displacement,  and  adding  thereto 
the  equal  wedge,  of  which  LOL'  is  a  section,  this  moment  is 
also  equal  to  twice  the  moment  of  either  wedge. 

The  moment  of  either  wedge  is 

/area  AWOW  XgOXdx 

where  gO  is  the  distance  of  the  centre  of  gravity  of  the 
triangle  from  0. 

But,  again,  since  A0  is  small, 

Area  &WOW  =  Y2yM-y  =  ^- 
and  00  =  %y 


:.BB'V  =  i-  X 


or  BM  = 

(where  Yzfy*dx  is  the  moment  of  inertia  of  the  load  water 
plane  about  its  longitudinal  axis,  which  is  called  "I".) 

The  calculation  of  BM  therefore  involves  the  calculation 
of  the  volume  of  displacement  and  the  transverse  moment 
of  inertia  of  the  load  water  plane. 

The  method  of  calculating  the  longitudinal  BM  is  along 
similar  lines. 

Other  stability  calculations  must  also  be  made  since  the 
metacentric  height  is  merely  an  index  of  the  initial  stability 
of  the  vessel.  These  calculations  are  long  and  involved, 
although,  like  the  other  ship  calculations,  they  are  based 
upon  a  simple  principle.  This  principle  is  briefly  expressed 


DESIGN  OF  SHIPS 


139 


by  an  equation  known  as  Atwood's  Formula  which  is  that 
the  moment  of  statical  stability  of  a  ship  when  inclined  to 
any  angle  6  is 

W  (V  Xyhh-    -  BG  sin  e\  foot  tons 

where  W    =  the  displacement  of  the  ship  in  tons 

V  =  the  displacement  of  the  ship  in  cu.  ft. 
v  =  the  volume  of  the  immersed  or  emerged  wedge 

in  cubic  feet 
hh'  =  the  horizontal  distance  between  the  centres 

of  gravity  of  the  two  wedges,  in  feet,  and 
BG  =  the  distance  between  the  centre  of  gravity  of 
the  ship  and  her  original  centre  of  buoyancy, 
in  feet. 


Moment  of  Statical  Stability  =  W 


FIG.  66.  —  Atwood's  formula. 

These  values  are  shown  in  Fig.  66,  and,  referring  to  that 
figure,  the  proof  of  Atwood's  formula  is  as  follows: 

The  couple  tending  to  right  the  ship  has  a  moment 
W  X  GZ  which  is  called  the  moment  of  statical  stability. 
But 

GZ  =  BR  -  BP  =  BR  -  BG  sin  6 

But  BR  represents  the  horizontal  shift  of  the  centre  of 


140  PRACTICAL  SHIP  PRODUCTION 

figure  of  the  volume  of  displacement  from  its  old  to  its 
new  position,  and  by  taking  moments : 

BR  X  V  =  v  Xhh' 
:.WXGZ  =W  p->yi/zL    .  BG  sin  01 

By  suitable  geometrical  and  arithmetical  calculations 
it  is  therefore  possible  to  find  the  moment  tending  to  right 
the  ship  when  heeled  to  any  angle  and  when  floating  at 
any  displacement.  By  dividing  each  moment  by  the  value 
of  the  displacement  the  corresponding  righting  arm  may  be 
obtained. 

If  several  different  displacements  be  considered  and 
righting  arms  calculated  for  different  inclinations,  it  is 
possible  to  plot  a  series  of  curves  with  righting  arms  as 
ordinates  and  displacements  as  abscissas.  Such  curves 
are  called  cross  curves  of  stability.  There  are  a  number  of 
different  methods  in  use  for  making  the  calculations 
by  which  data  for  plotting  these  cross  curves  is  obtained. 
Space  does  not  permit  going  into  detail  regarding  these 
methods  here.  All  are  based  upon  the  assuming  of  certain 
poles  about  which  the  ship  is  considered  as  inclined,  and 
corrections  must  be  made  to  obtain  the  true  righting  arms 
because  the  actual  locations  of  the  centre  of  gravity  of  the 
ship  are  different  from  those  assumed. 

By  making  these  corrections  it  is  possible  to  obtain, 
from  the  cross  curves,  certain  curves  showing,  for  various 
actual  displacements  and  corresponding  positions  of  the 
centre  of  gravity,  the  righting  arms  for  all  angles  of  in- 
clination. Such  curves  are  called  curves  of  statical  stability, 
and  are  similar  to  the  curve  shown  in  Fig.  7. 

The  statical  stability  at  any  angle  of  inclination  of  the 
ship  is  measured  by  the  moment  in  foot-tons  tending  to 
right  the  ship  when  she  is  inclined  to  that  angle.  The 
dynamical  stability  is  measured  by  the  amount  of  work 
that  must  be  done  in  bringing  the  ship  from  the  upright 
position  to  the  position  considered.  The  curve  of  dynamical 
stability  is  therefore  the  integral  of  the  curve  of  statical 


DESIGN  OF  SHIPS  141 

stability,  or  each  ordinate  of  the  curve  of  dynamical 
stability  may  be  calculated  by  obtaining  the  area  of  the 
curve  of  statical  stability  up  to  the  abscissa  corresponding 
to  the  angle  of  inclination  considered. 

In  addition  to  the  calculations  already  mentioned  there 
are  also  usually  made  calculations  for:  tons  per  inch 
immersion,  moment  to  change  trim  I",  areas  of  water 
lines,  longitudinal  C.G.  of  water  lines,  area  of  midship 
section,  correction  to  displacement  for  1  ft.  trim  by  stern, 
area  of  wetted  surface. 

The  tons  per  inch  immersion  for  any  given  draft  of  a 
ship  is  the  number  of  tons  increase  or  decrease  in  dis- 
placement that  will  be  caused  by  the  draft  being  increased 
or  decreased,  respectively,  by  1  inch.  Practically  speaking 
if  the  ship  sinks  1  inch  deeper  into  the  water  along  all  of 
her  water  line  the  increase  in  displacement  will  be  the 
volume  of  a  slice  1  inch  thick  and  having  the  area  of  the 
water  line.  (If  the  sides  of  the  ship  were  vertical  at  all 
points  this  would  be  absolutely  true) .  Hence  the  tons  per 
inch  immersion  is  found  by  dividing  the  area  of  the  water 
line  (in  square  feet)  by  12  X  35.  (Thickness  of  slice  is 
H2  fo°t  and  there  are  35  cubic  feet  of  salt  water  to  the  ton. 
For  fresh  water  the  figure  to  be  used  is  36  instead  of  35.) 

The  moment  to  change  trim  I  inch  is  the  longitudinal 
moment,  in  foot-tons,  necessary  to  cause  the  ship  to  change 
her  trim  by  1  inch  from  the  water  line  at  which  she  is  con- 
sidered to  be  floating.  It  is  equal  to  }{ 2  of  the  displace- 
ment in  tons,  multiplied  by  the  longitudinal  metacentric 
height  in  feet,  divided  by  the  length  on  the  water  line  con- 
sidered, in  feet.  The  reason  for  this  is  that  when  the  ship 
changes  trim  1  inch  she  is  inclined  longitudinally  to  an  angle 
with  her  original  position  of  which  the  tangent  is  K2  f°°t 
divided  by  the  length  of  the  water  line  in  feet,  this  inclina- 
tion also  having  for  its  tangent  the  distance  that  the  ship's 
centre  of  gravity  may  be  considered  as  moving  longitudi- 
nally divided  by  the  longitudinal  metacentric  height.  (The 
center  of  gravity  is  here  considered  as  moving  from  G  to 
G'  because  of  the  moving  of  a  weight  of  w  tons,  longitudi- 


142  PRACTICAL  SHIP  PRODUCTION 

nally,  through  a  distance  of  d  feet.     The  moment  causing 
the  change  of  trim  is  then  w  X  d  foot-tons.) 

Hence,  if  0  be  the  angle  of  longitudinal  inclination 


=  -rTf  =    r-  (where   L    is    the  length  in  feet). 


But  W  X  GG'  =  w  X  d  (where  W  =  displacement  in  tons). 

(Since  the  ratio  of  the  shifts  of  the  centres  of  gravity  of  the 
ship  and  the  weight  moved  is  the  inverse  of  the  ratio  of 
their  respective  weights)  . 

Hence  the  moment  to  change  trim  1  inch  or 


The  calculations  of  the  areas  of  water  line,  position  of 
longitudinal  centre  of  gravity  of  water  line,  area  of  midship 
section,  and  correction  to  displacement  for  1  foot  trim  by 
the  stern  for  any  given  water  line,  are  made  by  the  methods 
described  below,  being  simply  geometrical  calculations. 
By  making  calculations  of  each  for  several  different  water 
lines  curves  can  be  plotted  giving  values  for  all  inter- 
mediate points. 

The  correction  to  displacement  for  1  foot  trim  by  the  stern 
is  the  amount  that  must  be  added,  in  order  to  obtain  the 
true  displacement,  to  the  displacement  corresponding 
to  a  water  line  drawn  parallel  to  the  load  water  line  and  at 
a  level  corresponding  to  the  mean  draft  at  which  the  ship 
is  floating.  When  the  ship  changes  trim  the  shape  of  the 
water  line  changes  on  account  of  the  difference  between  the 
form  of  the  molded  surface  at  the  forward  and  after  ends. 
Since  displacements  are  ordinarily  calculated  only  for  water 
lines  corresponding  to  various  drafts  on  an  even  keel  it  is 
necessary  to  have  a  means  of  correcting  these  to  find  the 
displacements  when  floating  out  of  the  designed  trim. 


The  correction  is  —  j  —  tons  (additive) 


DESIGN  OF  SHIPS  143 

where  T  is  the  tons  per  inch  immersion, 

L  is  the  length  of  the  water  line  in  feet,  and 
d  is  the  distance  that  the  centre  of  gravity  of  the 
load  water  plane  is  aft  of  amidships,  in  feet. 

(Should  the  centre  of  gravity  of  the  water  plane  be 
forward  of  amidships  the  correction  will,  of  course,  be 
subtractive  instead  of  additive.) 

The  area  of  wetted  surface  is  calculated  for  use  in  figuring 
the  frictional  resistance  of  the  ship.  It  cannot  be  calculated 
exactly  on  account  of  the  ship's  surface  being  undevelop- 
able, but  for  practical  purposes,  different  approximate 
methods  can  be  used  which  give  sufficient  accuracy. 

One  of  these,  known  as  Kirk's  Analysis  consists  in  cal- 
culating the  wetted  surface  by  the  expression 

(2LD  +  ex  LB) 

where  L  is  the  length  of  the  ship,  in  feet, 
D  is  the  draft  of  the  ship,  in  feet, 
B  is  the  beam  of  the  ship,  in  feet, 
oc  is  the  block  coefficient  of  fineness, 
•   and  the  resulting  value  is  the  total  area  of  the 
wetted  surface  in  square  feet. 

Other  approximate  formulas  for   the  wetted  surface,  in 
square  feet  are: 
Admiral  Taylor's: — 

15.5VWX 

where  W=  displacement,  in  tons,  and   j 
L  =  length,  in  feet. 

Mr.  Denny's:— 

1.7LD  +  J 

where  L  =  length,  D  =  draft  (feet)  and 

V  =  volume  of  displacement  (cubic  feet) . 

A  more  accurate  calculation  can  be  made  by  finding  the 
area  of  a  curve  of  modified  girths,  each  girth  being  taken 


144 


PRACTICAL  SHIP  PRODUCTION 


along  a  frame  station  and  increased  by  multiplying  it  by 
the  average  secant  of  the  angle  between  the  molded  surface 
and  a  fore  and  aft  line  taken  at  the  station  considered. 

The  methods  of  making  the  various  calculations  outlined 
in  the  preceding  paragraphs  are  based  upon  various  means 


(A)  ^ 


yz)h  + 


c      Trapezoidal  Rule : — 
Area  ABCD  =  $(y 

2/3 

Simpson's  First  Rule : — 
D          Area  ABCD  =  -=  (yi  +  4y2  +  j/3) 


+ 


2/3 


Trapezoidal  Rule : 

Area  ABCD  =  h\y~  +  y2+y3  +  ~ 


Simpson's  Second  Rule : — 
Area  ABCD  =  p(?/i  +  3y*  +  37/3  + 


11  Five -Eight "  Rule  :— 

Area  ABMN  (in  diagram  (A)) 


-2/3) 


In  General  :  — 


•O 


FIG.  67. — Methods  of  integration. 

of  integration,  it  being  necessary  in  the  case  of  a  ship  to 
obtain  certain  areas,  volumes,  moments,  and  moments  of 
inertia  of  curvilinear  areas  and  volumes,  not  susceptible 
of  exact  mathematical  calculation. 


DESIGN  OF  SHIPS  145 

These  are  most  commonly  obtained  by  the  Trapezoidal 
Rule,  Simpson's  Rules,  and  graphically  by  means  of  the 
planimeter  and  integrator. 

The  trapezoidal  rule  is  used  when  it  is  assumed  that  the 
ordinates  are  so  closely  spaced  that  the  curve  between  any 
two  adjacent  ordinates  may  be  considered,  for  all  practical 
purposes,  as  a  straight  line.  For  a  convex  curve  this  gives 
too  small  an  area  (see  Fig.  67). 

Simpson's  Rules  are  shown  in  Fig.  67.  These  may  be 
extended  to  a  large  number  of  intervals,  it  being  noted 
that  the  first  rule  applies  when  the  number  of  intervals  is 
even;  and  the  second  when  it  is  a  multiple  of  three.  The 
five-eight  rule  may  be  used  to  find  the  area  between  two 
successive  ordinates  in  cases  where  the  number  of  intervals 
is  neither  even  nor  a  multiple  of  three. 

Both  Simpson's  and  the  trapezoidal  rules  furnish  an 
arithmetical  means  of  finding  the  value  of  J*ydx  (see  Fig. 
67).  If  the  value  sought  were  fy^dx  the  same  method 
might  be  followed — only  that  in  this  case  the  square 
of  each  ordinate  would  be  considered — and  so  in  the 
case  of  any  function  of  the  ordinates. 

The  detailed  methods  of  making  the  calculations  outlined 
above  form  the  subject  of  Theoretical  Naval  Architecture 
which  is  too  large  a  subject  to  be  treated  here.  The  reader 
is  referred,  for  complete  information  regarding  these 
matters,  to  such  books  as 

Attwood's  "Text  Book  of  Theoretical  Naval  Architecture." 

Robinson's  "  Naval  Construction." 

Biles'  "The  Design  and  Construction  of  Ships." 

Peabody's  "Naval  Architecture." 

White's  "Manual  of  Naval  Architecture." 

Reed's  "Stability  of  Ships." 

After  the  displacement,  weight  and  stability  calculations 
have  been  made,  it  may  be  found  that  certain  shifts  of 
weights,  or  even  changes  in  the  lines  will  be  required  in 
order  to  give  satisfactory  conditions  of  draft,  trim,  buoy- 
ancy, and  stability.  When  these  changes  have  been  made 

10 


146  PRACTICAL  SHIP  PRODUCTION 

the   calculations   must   be   made    over    again — in    whole 
or  in  part. 

When  the  locations  arid  amounts  of  weights  have  been 
so  adjusted,  with  respect  to  the  lines,  as  to  give  satisfactory 
conditions,  the  principal  plans  are  completed  and  the  cal- 
culations for  strength  outlined  on  pages  25  to  27  are  made. 
Such  changes  in  weights,  as  may  be  found  necessary  as  a 
result  of  these  calculations  may  possibly  result  in  the  ne- 
cessity for  further  changes  in  the  preceding  calculations— 
although  this  is  not  usually  the  case. 

6.  DETAIL  PLANS  AND  SPECIFICATIONS 

The  remainder  of  the  design  of  the  ship  consists  in  the 
preparation  of  detail  plans  for  the  various  minor  parts, 
fittings,  installations,  etc.,  not  shown  in  the  principal  plans, 
but  necessary  for  the  work  of  the  shipbuilders.  The  num- 
ber and  extent  of  these  plans  vary  with  the  size  and  type 
of  ship  and  the  requirements  of  the  prospective  owner. 

In  addition  to  the  plans  specifications  are  prepared  which 
supplement  the  plans,  and  embody  instructions  to  the 
builders  as  to  the  quality  and  sizes  of  the  various  materials 
to  be  used  in  the  construction  of  the  ship,  and  numerous 
other  requirements  to  be  complied  with  that  are  not  fully 
shown  in  the  plans. 

Based  upon  the  plans  and  specifications  there  are  also 
usually  prepared,  under  the  direction  of  the  designer,  lists 
of  materials  that  will  be  required  for  the  building  of  the 
ship. 


CHAPTER  V 
SHIPYARDS 

1.  SITE  FOR  A  SHIPYARD 

The  site  for  a  shipyard  must  be,  of  course,  on  the  edge  of 
some  body  of  water  of  sufficient  depth,  and  extent,  to  per- 
mit of  safe  launching  of  the  ships  after  they  have  been  built. 
It  must  also  be  so  chosen  as  to  permit  of  expeditious  deliv- 
ery of  the  large  and  heavy  materials  required  for  building 
the  ships,  and  should,  if  possible,  be  located  not  too  far 
from  suitable  housing  facilities  for  the  workmen  who  are 
to  be  employed.  Not  only  must  there  be  sufficient  water 
for  launching  the  ships  but  also  there  must  be  a  channel 
leading  to  the  sea  through  which  the  ships  may  pass  after 
they  are  entirely  completed  and  outfitted. 

The  area  of  ground  necessary  for  a  shipyard  depends 
not  only  upon  the  number  and  size  of  the  ships  to  be  built 
but  also  upon  their  character,  and  how  much  of  the  work 
of  fitting  out  and  equipping  the  hulls  is  to  be  done  entirely 
by  the  shipbuilder  and  at  the  shipyard.  Some  shipbuilders 
do  practically  all  of  the  work,  including  the  manufacture 
of  engines,  boilers,  large  castings,  forgings,  etc.,  in  their 
own  yards.  Others  confine  their  work  almost  entirely  to 
the  hull  proper  and  purchase  a  large  amount  of  material, 
ready  for  installation,  from  other  concerns.  In  the  case 
of  " fabricated  ships"  even  the  parts  of  the  hull  are  made  at 
a  distance  and  shipped  to  the  yard  for  erection  and  assembly. 

No  fixed  rule  can  therefore  be  given  regarding  the  acreage 
required  for  a  shipyard,  but  this  can  be  roughly  determined, 
having  due  regard  for  the  conditions  to  be  met,  by  compari- 
son with  other  established  yards. 

2.  THE  BUILDING  SLIP  AND  LAUNCHING  WAYS 

The  first  essential  in  a  shipyard  is  the  place  in  which 
actually  to  build  the  ships.  The  hull  of  a  modern  ship, 

147 


148  PRACTICAL  SHIP  PRODUCTION 

when  ready  for  launching,  weighs  a  good  many  hundreds, 
or  perhaps  thousands,  of  tons  and  this  large  and  relatively 
concentrated  weight  must  be  properly  supported. 

It  is  therefore  customary,  in  most  cases,  to  strengthen 
the  ground  on  which  a  ship  is  to  be  built  by  means  of  piling. 
In  some  cases — as  where  the  site  of  the  shipyard  is  over 
a  stratum  of  rock,  or  where  the  ground  is  very  hard- 
piling  is  not  necessary,  but  where  the  ships  to  be  built 
are  large,  and  except  in  rare  instances,  piling  is  commonly 
used.  Sometimes  the  piling  may  be  of  reinforced  concrete, 
but  more  often  it  is  of  wood. 

In  addition  to  the  driving  of  piles  it  is  very  often  nec- 
essary to  do  considerable  excavating  and  dredging  in  order 
to  provide  proper  facilities  for  the  building  and  launching 
of  ships.  Fig.  68  shows,  in  cross  section,  the  site  of  a 
shipyard  before  and  after  the  dredging,  excavating  and 
pile  driving  have  been  done. 

The  space  over  which  a  ship  is  built  is  called  the  building 
slip.  This  ground  except  where  rocky,  or  very  hard,  is 
reinforced  by  the  piles,  which  are  driven  deep  into  the 
ground  until  they  strike  gravel  or  other  firm  subsoil.  The 
keel  line  of  the  ship,  while  being  built,  is  usually  nearly 
normal  to  the  line  of  the  water's  edge,  although,  in  some 
cases,  where  the  breadth  of  the  water  into  which  the  ship 
is  to  be  launched  is  limited,  it  is  necessary  to  have  the 
building  slip  inclined  to  the  line  of  the  water's  edge  (or 
even  broadside  launching  may  be  necessary.  See  page  157) . 

The  piles  are  driven  in  rows  at  right  angles  to  the  keel 
line.  The  spacing  of  these  rows  varies  with  the  weight  of 
the  ship  and  hardness  of  the  ground.  In  most  cases  it  is 
about  four  feet  although  in  some  cases  it  may  be  as  great 
as  six  feet.  For  battleships  and  large,  heavy  vessels  it 
may  be  as  close  as  two  feet. 

There  are  three  lines  along  the  building  slip  that  must 
be  strongly  reinforced  by  piling :  the  line  of  the  keel,  which 
takes  a  large  part  of  the  weight  of  the  ship  during  the  proc- 
ess of  construction,  and  the  two  lines,  parallel  to  the  keel 
line  on  which,  later,  are  laid  the  launching  ways,  heavy 


SHIPYARDS 


149 


is 

O  «*-( 
0»  <D 
CO  .Q 


150  PRACTICAL  SHIP  PRODUCTION 

timbers,  which  take  the  weight  of  the  ship  when  she  is 
launched.  In  addition  to  these  lines  practically  all  of  the 
ground  under  the  ship's  bottom  must  have  a  certain 
amount  of  reinforcing  to  take  shores  and  blocks  used  to 
support  the  bottom  and  bilges  of  the  ship  during  her 
construction. 

The  piles  are  usually  pine  or  fir  stems  about  10"  or  12" 
in  diameter  at  the  butts  and  of  lengths,  dependent  upon 
the  nature  of  the  ground,  of  sometimes  as  much  as  50  feet. 
The  exact  number  and  arrangement  of  the  piles  must  be 
decided  in  each  case.  It  is  well,  however,  in  laying  out  a 
new  building  slip  to  consider  the  possibility  of  larger  and 
heavier  ships  being  built  subsequently  on  the  same  slip. 

For  a  large,  heavy  ship,  such  as  a  modern  battleship,  it  is 
not  unusual  to  find  the  piles  under  the  launching  ways  in 
groups  of  six,  spaced  about  16"  between  centres,  the  groups 
being  four  feet  apart  along  the  lines  of  the  ways.  Under 
the  middle  portion  of  the  keel  the  rows  may  be  two  feet  apart 
with  eight  piles  in  alternate  groups  and  two  piles  in  the 
intermediate  groups,  and  under  the  first  docking  keels 
groups  of  six  piles  each  spaced  every  four  feet.  After  the 
piles  have  been  driven  their  tops  are  sawed  off  and  on  them 
are  placed  large  cross  logs  secured  with  heavy  driving  bolts. 
The  cross  logs  may  extend  across  the  full  width  of  the  ship 
at  eight-foot  intervals  of  the  length,  the  intermediate  logs 
being  of  shorter  lengths.  Sometimes  the  piles  are  not 
sawed  off  at  the  ground  level,  but  at  a  considerable  dis- 
tance above  it,  and  a  platform  of  heavy  planking  is  built 
over  them  as  shown  in  Fig.  69. 

Along  the  middle  of  the  slip  are  laid  large  blocks  from 
12"  to  18"  square,  upon  which  is  laid  the  keel  of  the  ship. 
These  blocks  are  placed  over  the  cross  logs  and  are  built  up 
to  a  considerable  height  above  the  ground  so  as  to  give 
workmen  ready  access  to  the  bottom  of  the  ship,  and  to 
give  sufficient  room  for  launching.  A  height  of  at  least 
four  feet  should  be  allowed  (see  Figs.  69  and  70) — and  usu- 
ally a  little  more — for  this  purpose.  The  lower  blocks  are 
usually  six  or  seven  feet  long,  the  upper  ones  shorter.  The 


SHIPYARDS 


151 


152 


PRACTICAL  SHIP  PRODUCTION 


line  of  the  top  of  the  keel  blocks  is  inclined  so  that  the  end 
at  the  water's  edge  is  lower  than  the  other  end.  This 
slope  is  usually  slightly  greater  than  %"  per  foot.  In  the 
case  of  long,  light  ships  it  may  be  as  much  as  l^{ 6"  per 
foot.  For  battleships  and  cruisers  it  is  generally  -KG" 
per  foot.  The  larger  the  vessel  the  less  the  declivity. 

The  declivity  for  the  launching  ways,  down  which  the 
ship  slides  into  the  water  after  the  hull  is  built,  is  greater, 
ordinarily,  than  that  of  the  keel  blocks,  being  usually 
I^{Q"  or  Y±'  to  the  foot.  In  some  cases  the  top  of  the 
launching  ways  at  the  end  near  the  water  is  given  a  longi- 
tudinal curvature  [or  camber  (of  from  J£2"  to  }{Q"  per 


-Bottom  of  Ship 


Piling 


Ground. 


FIG.  70. — Keel  blocks  and  piling. 


foot)  so  as  to  give  an  increasing  declivity  at  the  lower 
end.  These  ways  may  also  have  a  slight  transverse  cant 
inboard  (about  J^"  per  foot). 

The  launching  ways  are  usually  located  at  about  %  of 
the  beam  of  the  ship  out  from  the  keel  on  each  side  so  that 
their  distance  apart  is  about  J£  of  the  width  of  the  hull. 
The  size  of  the  launching  ways  varies  from  about  15" 
breadth  by  9"  depth  in  smaller  vessels  to  as  high  as  6 
feet  breadth  by  16"  or  18"  depth  in  the  case  of  very  large 
vessels.  The  breadth  must  be  so  proportioned,  with 
regard  to  the  launching  weight  of  the  ship,  as  to  give  a 
bearing  pressure  of  about  2  to  2>^  tons  per  square  foot. 


SHIPYARDS  153 

Pressures  of  2^  tons  per  square  foot  should  never  be  ex- 
ceeded. The  materials  commonly  used  are  yellow  pine, 
elm,  or  oak.  A  cross  section  of  a  ship  on  the  launching 
ways  is  shown  in  Fig.  71. 

The  launching  ways  must  be  extended  for  some  distance 
beyond  the  water's  edge,  together  with  the  necessary  sup- 
porting piles,  so  that  there  will  be  several  feet  of  water 
(from  4  or  5  feet  for  smaller  vessels  to  10  or  12  for  larger 
ones)  over  the  end  of  the  ways  when  the  ship  is  launched 


Cross  W  HlJiW^^         Pi'toB 

S^YyV/i^'^/t  YVyMS' T   » V^ 

FIG.  71. — Ship  on  launching  ways. 

(see  Figs.  68,  72  and  73).     The  rise  and  fall  of  the  tide  must, 
of  course,  be  considered  in  this  connection. 

In  designing  the  building  slip,  with  regard  for  both  the 
keel  blocks  and  launching  ways  due  consideration  must  be 
given  to  the  contour  of  the  ground,  and  of  the  bottom  of  the 
water,  and  to  the  shape,  weight  and  size  of  the  ship  to  be 
built  and  launched.  Certain  calculations  should  be  made 
regarding  the  probable  behavior  of  the  ship  when  launched 
in  order  to  make  certain  that  the  launching  ways,  especially 


154 


PRACTICAL  SHIP  PRODUCTION 


SHIPYARDS  155 

at  their  lower  end,  have  been  properly  designed.  These 
investigations  must  be  made,  even  before  the  commence- 
ment of  the  actual  building  of  the  ship,  since  the  driving 
of  the  piling,  the  necessary  dredging  work  involved,  etc., 
usually  must  all  be  accomplished  before  the  laying  of  the 
keel.  ' 

In  Fig.  72,  top  view,  is  shown  a  sectional  profile  of  the 
ground  and  water  with  piling,  launching  ways  and  ship 
on  the  ways,  ready  to  be  launched.  The  launching  con- 
sists in  permitting  the  ship,  with  supporting  cribwork, 
to  slide  down  the  launching  ways  into  the  water.  As 
soon  as  the  stern  enters  the  water  there  is  added,  to  the 
upward  force  given  by  the  support  of  the  launching  ways, 
the  upward  force  of  buoyancy  due  to  the  amount  of  the 
hull  that  is  submerged.  As  the  downward  motion  of  the 
ship  continues,  the  amount  of  this  force  of  buoyancy 
increases,  but  after  the  stern  passes  the  end  of  the  launching 
ways  it  loses  the  upward  support  of  these  ways,  and  if  the 
force  of  buoyancy  is  not  great  enough  the  ship  may  "tip." 
Such  "tipping"  is  shown  in  the  middle  diagram  of  Fig. 
72,  and  should  always  be  avoided,  since  the  ship  would 
very  probably  be  seriously  damaged  by  the  great  con- 
centrated force  thus  brought  to  bear  on  the  portion  of  the 
hull  directly  over  the  end  of  the  launching  ways — if  the 
ways  themselves  were  not  crushed  in,  thus  also  endangering 
the  hull. 

On  the  other  hand  if  a  certain  amount  of  the  support  of 
the  ship  is  not  soon  transferred  from  the  launching  ways 
to  the  buoyancy  of  the  water  beyond  the  end  of  the  ways, 
the  ship  may  "pivot"  about  her  bow  or  a  point  near  the 
bow.  Such  " pivoting"  is  shown  in  the  bottom  view  of 
Fig.  72.  In  the  case  of  a  very  long,  light  vessel,  like  a 
destroyer,  premature  pivoting  might  cause  excessive  longi- 
tudinal stresses  in  the  hull  and  result  in  serious  damage. 
(Pivoting  at  the  proper  stage  of  the  launching  is  not  only 
not  dangerous,  but  is  desirable.) 

Both  tipping  and  pivoting  must  therefore  be  carefully 
considered  and  the  launching  ways  must  be  extended  far 


156  PRACTICAL  SHIP  PRODUCTION 

enough  into  the  water  to  prevent  tipping  and  not  so 
deeply  as  to  cause  premature  pivoting.  The  ways  should 
be  so  designed,  however,  that  the  ship  will  pivot  after 
a  good  proportion  of  her  length  is  in  the  water. 

It  is  necessary  to  provide  sufficient  depth  of  water  to 
prevent  the  bow  from  striking  bottom  during  launching. 
As  will  be  seen  in  Figs.  68  and  72,  the  depth  of  water  just 
beyond  the  end  of  the  launching  ways  should  increase 
quite  rapidly. 

Summary  of  Requirements  of  Building  Slip,  Launching  Ways,  Etc. 

The  most  important  points  to  be  looked  out  for  in  laying 
out  the  piling,  etc.,  for  a  building  slip  may  be  summarized 
as  follows: 

1.  The  piles  must  be  so  arranged  as  to  give  sufficient 
support  for  the  launching  weight  of  the  hull. 

2.  There  must  be  sufficient  breadth  of  water  in  the  line 
of  the  launching  ways,  produced,  to  prevent  the  ship  from 
striking  the  opposite  bank  when  launched. 

3.  There  must  be  sufficient  depth  of  water  along  this 
line  so  that  the  hull  will  not  strike  bottom  when  launched — 
especially  just  beyond  the  end  of  the  launching  ways. 

4.  The  distance  apart  of  the  launching  ways  must  be 
such  that  the  weight  of  the  ship  will  be  well  transmitted 
through  heavy  vertical  longitudinal  members  of  the  hull, 
and  properly  distributed  athwartships. 

5.  The   launching   ways   must  not  be  too  far  apart, 
because,  owing  to  the  fineness  of  the  ends,  a  sufficient 
amount  of  the  length  might  then  not  be  supported,  and  too 
much  transverse  stress  thus  be  caused. 

6.  The  launching  ways  must  not  be  too  near  together — 
which  would  cause  undue  transverse  stresses  and  decreased 
stability. 

7.  The  launching  ways  must  extend  far  enough  into  the 
water  to  prevent  tipping. 

8.  The  launching  ways  must  not   extend    too    deeply 
into  the  water  or  otherwise  pivoting  may  occur  too  soon, 


SHIPYARDS  157 

9.  The  height  of  the   keel   blocks   must   be   sufficient 
to  permit  ready  access  to  the  ship's  bottom  for  men  working 
on  her  construction. 

10.  The  height  of  the  launching  ways  must  be  such  as 
to  permit  an  unobstructed  slide  of  the  ship  down  them 
when  launched. 

(For  additional  information  on  this  subject  see  Chap. 
VII,  Sect.  7.) 

In  the  great  majority  of  shipyards  the  building  slips 
and  launching  ways  are  arranged  in  the  manner  just 
described,  but  in  some  yards,  notably  those  on  the  Great 
Lakes,  ships  are  launched  broadside  on,  being  built  with 
their  keels  parallel  to  instead  of  perpendicular  to  the 
water  front.  In  such  cases  instead  of  two  there  are  laid 
a  number  of  launching  ways  usually  at  10  or  15  foot 
intervals  along  the  length  of  the  ship  and  they  are  given 
a  much  greater  declivity  than  ways  for  end  launchings. 
One  of  the  advantages  of  this  method  is  that,  due  to  her 
striking  the  water  broadside  on,  the  ship  is  checked  quickly, 
and  does  not  require  a  broad  expanse  of  water.  One  of 
the  disadvantages  is  that  a  much  greater  extent  of  water 
front  is  required,  which  on  the  seaboard,  where  water 
front  is  usually  costly,  may  be  a  serious  drawback.  In 
the  shipyard  shown  in  Fig.  73  about  four  times  as  much 
water  front  would  be  required  if  the  28  ships  were  all  to 
be  built  at  the  same  time  for  broadside  launchings  instead 
of  as  shown. 

3.  YARD  LAY-OUT—SHOPS,  BUILDINGS,  ETC. 

In  laying  out  a  shipyard  it  is  important  to  remember 
the  various  processes  in  the  building  of  a  ship,  from  the 
time  that  the  raw  material  is  received  in  the  yard  until 
the  time  when  it  is  secured  in  place  in  the  vessel. 
Provision  must  be  made  for  stowing  the  material  until 
it  is  needed,  and  for  "  fabricating "  it,  or  fashioning  it 
to  the  shapes  and  sizes  necessary  for  its  assembly  in 
the  ship.  The  layout  of  storehouses,  stowage  spaces, 
shops,  etc.,  should  therefore  be  so  arranged  as  to  require 


158  PRACTICAL  SHIP  PRODUCTION 

the  minimum  amount  of  transporting  and  handling  of 
both  raw  and  fabricated  material.  This  is  not  a  simple 
matter,  since  so  many  different  elements  enter  into  the 
problem,  but  certain  salient  points  may  always  be  looked 
out  for. 

In  general,  the  route  to  be  followed  by  the  structural 
steel  from  the  stowage  racks  should  be  in  a  nearly  straight 
line  by  way  of  the  laying  out  shed,  punching  and  shearing 
shed,  and  fabricating  shop  to  the  building  slip,  with  as 
short  distances  between  each  as  possible.  A  similar  principle 
applies  to  the  engine  parts  which  should  go  from  foundry 
or  forge,  via  machine  shop  and  erecting  room  to  the  ship. 

Means  for  transportation  between  these  various  points 
and  for  handling  and  placing  heavy  weights  on  the  ship 
must  also  be  provided  and  the  more  complete  the  equipment 
of  a  yard  in  this  respect,  the  more  efficient  will  be  its 
operation. 

For  transporting  large  quantities  of  raw  materials,  or 
heavy  forgings,  castings  and  machinery  parts  about  the 
yard  ordinary  railroad  standard  gauge  tracks  are  usually 
laid,  with  suitable  spurs,  switches  and  connections,  if 
possible,  to  the  local  railroad  tracks.  The  yard  should 
be  equipped  with  a  certain  number  of  railway  locomotives 
and  freight  cars  of  its  own. 

For  smaller  weights  narrow  gauge  tracks  are  provided 
on  which  small  flat  cars  may  be  pushed  by  hand.  Motor 
trucks  are  also  often  employed.  In  the  different  shops 
various  overhead  and  jib  cranes  are  used  for  local  handling. 

A  well-equipped  yard  should  also  have  a  number  of 
locomotive  cranes  capable  of  lifting,  transporting,  and 
handling  weights  up  to  from  ten  to  twenty  tons.  These 
should  run  on  the  standard  gauge  railway  tracks. 

Large  traveling  cranes  are  also  very  desirable  for  ship- 
yards of  any  importance.  These  run  on  specially  con- 
structed tracks  of  very  wide  gauge  and  are  capable  of 
negotiating  very  large  weights — of  fifty  tons  or  more. 
These  are  especially  useful  in  installing  engines,  boilers, 
armor,  and  other  heavy  weights  in  large  vessels  alongside  of 


SHIPYARDS  159 

the  fitting  out  piers,  at  which  the  ships  are  moored  after 
launching  and  prior  to  final  completion,  and  with  at  least 
one  of  which  every  important  yard  should  be  supplied. 

One  large  floating  derrick  or  crane  capable  of  handling 
very  heavy  weights  (100  to  150  tons)  is  also  very  desirable, 
although  these  are,  of  course,  very  costly  and  not  possessed 
by  many  shipyards. 

For  handling  and  erecting  material  in  place  in  the  ship 
on  the  building  slip  it  is  necessary  that  certain  other  cranes 
or  derricks  be  provided.  Various  types  are  in  use  but 
all  should  be  so  arranged  that  a  weight  may  be  lowered 
over  any  point  of  the  ship's  hull  for  each  building  slip  or 
berth. 

One  method  is  to  have  a  number  of  fixed  masts  or  derricks 
each  equipped  with  one  or  more  booms  operated  by  hoisting 
engines.  These  derricks  must  be  more  or  less  numerous 
since  each  can  handle  material  over  only  a  limited  circle 
(see  Fig.  73). 

A  better,  but  more  expensive,  arrangement,  is  to  have  high 
trestles  running  parallel  to  the  centre  line  of  the  building 
slip  for  traveling  cranes  which  may  be  either  of  the  canti- 
lever, overhead,  or  gantry  type. 

A  birdseye  view  of  the  shipyard  of  the  Submarine  Boat 
Corporation  is  shown  in  Fig.  73,  in  which  will  be  seen  the 
building  slips,  launching  ways,  fitting  out  piers,  derricks,  a 
large  cantilever  crane,  shops,  buildings,  railway  tracks,  etc. 
This  yard,  being  designed  to  build  " fabricated"  ships, 
does  not  have  the  variety  of  shops  found  in  some  yards. 

The  buildings,  etc.,  necessary  for  a  shipyard  usually 
include  the  following: 

1.  Buildings  for  offices,  drafting  rooms,  etc. 

2.  Store  houses  and  plate,  angle,  and  other  racks. 

3.  Power  house  (unless  power  is  furnished  by  outside  plant). 

4.  Mold  loft. 

5.  Bending  slabs. 

6.  Laying  out,  punching,  and  shearing  sheds. 

7.  Fabricating  and  erecting  shops. 

8.  Smith  shop. 


160 


PRACTICAL  SHIP  PRODUCTION 


SHIPYARDS  161 

9.  Pattern  shop. 

10.  Foundry. 

11.  Machine  shop. 

12.  Plumbers'  and  pipefitters'  shop. 

13.  Joiner  shop. 

14.  Shipwrights'  and  sparmakers'  shop. 

15.  Coppersmiths'  shop. 

16.  Sheet  metal  shop. 

17.  Boiler  shop. 

18.  Sail  loft. 

19.  Rigging  loft. 

20.  Electrical  shop. 

21.  Pickling,  galvanizing  and  plating  shops. 

22.  Paint  and  varnish  shop. 

23.  Boat  shop. 

24.  Upholstery  shop. 

Among  these  the  following  may  be  noted  especially: 
Storehouses  are  necessary  in  considerable  variety  and 
should  be  located  conveniently  to  the  shops  requiring  the 
largest  quantities  of  the  materials  stored  in  each.  Plate 
racks  should  be  provided  so  that  plates  may  be  stowed  on 
edge  by  various  sizes  so  as  to  be  readily  accessible.  This 
is  usually  accomplished  by  means  of  posts  or  metal  bars 
set  in  concrete  foundations,  against  which  the  plates  may 
lean.  For  angles  and  other  shapes  a  good  arrangement  is 
to  have  vertical  metal  posts  with  horizontal  arms  extending 
out  on  each  side  at  various  heights,  the  upper  ones  usually 
being  shorter  and  each  successive  arm  being  slightly  longer 
than  the  one  above. 

The  mold  loft  is  a  building  or  shed  of  great  horizontal 
extent  which  permits  of  its  having  a  large  continuous 
floor  of  sufficient  size  to  have  drawn  on  it  the  lines  of  the 
ship  to  full  scale.  The  plans  of  a  ship  to  be  built  are 
furnished  to  the  mold  loft  by  the  drafting  room,  and  from 
these  plans  the  workers  in  the  mold  loft,  called  loftsmen, 
lay  down  and  fair  up,  to  full  scale,  the  lines  of  the  ship, 
and  make  templates  for  laying  out  the  material  for  the 
hull.  Templates  are  thin  wood  or  paper  patterns  which 
show  the  size,  shape,  locations  and  sizes  of  rivet  holes,  and 
other  particulars  of  the  parts  to  which  they  apply. 
11 


162  PRACTICAL  SHIP  PRODUCTION 

The  bending  slabs  are  heavy  rectangular  cast  iron  blocks 
or  slabs,  square,  or  nearly  square,  and  usually  five  or  six 
feet  on  a  side  and  from  2  or  3  inches  to  5  or  6  inches  thick 
placed  together,  side  to  side,  and  end  to  end,  so  as  to  form 
a  large  horizontal  flat  surface  on  top  of  which  the  frames, 
reverse  frames,  and  other  similar  parts  of  a  ship  can  be 
bent  to  their  proper  shapes.  The  slabs  are  usually  laid 
on  top  of  heavy  timbers  which  thus  raise  them  a  foot  or 
more  above  the  ground  or  floor  of  the  shed  in  which  they 
are  located.  They  have  small  holes  (usually  about  1J^" 
square)  running  vertically  through  them,  so  that  their 
upper  surface  presents  a  lattice-like  appearance  as  shown 
in  Fig.  78.  These  holes  are  used  for  the  insertion  of  dogs, 
pins,  etc.,  by  means  of  which  the  frame  bars  are  clamped 
down  and  held  to  the  proper  shape  while  being  bent  and 
beveled. 

Close  to  the  slabs  are  located  long  furnaces,  of  the  re- 
verberatory  type,  usually  oil-burning,  for  heating  the 
frames. 

The  laying-out  shed  should  be  located  near  the  mold 
loft.  Templates  from  the  latter  are  used  for  laying  out 
the  various  plates  and  shapes  for  fabrication  in  this  shed 
which  often  forms  a  part  of  the  punching  and  shearing,  or 
as  it  is  sometimes  called,  the  plate  and  angle  shop.  In 
this  latter  shop  are  located  the  various  machine  tools  used 
for  punching,  shearing  and  planing,  etc.,  the  various 
steel  parts  of  the  hull  that  have  been  marked  in  the  laying 
out  shed  for  that  purpose. 

The  fabricating  and  erecting  shop  may  also  form  a  part 
of  the  plate  and  angle  shed  or  it  may  be  in  another  building 
close  by.  Here  various  small  portions  of  the  ship's  struc- 
ture, such  as  floor  plates,  hatch  coamings  and  covers, 
water-tight  doors,  skylights,  trunks,  etc.,  are  assembled 
and  riveted  up  so  that  they  may  be  taken  to  the  ship  ready 
for  installation. 

The  smith  shop  usually  has  both  small  forges  and  anvlis 
for  hand  forgings,  and  steam  hammers  and  large  furnaces 
for  heavy  work,  and  drop  forgings.  The  extent  of  the 


SHIPYARDS  163 

forging  work  varies  in  different  yards,  some  having  many 
of  the  larger  forgings  made  by  outside  concerns. 

In  the  joiner  shop  a  great  part  of  the  wood  work  of  the 
ship  is  done.  Furniture,  ladders,  wooden  doors,  sky- 
lights, chests,  lockers,  gangways,  gratings,  and  a  large 
number  of  other  miscellaneous  wooden  articles  are  made 
here. 

In  the  shipwright  shop  material  for  wood  decks,  founda- 
tions, masts,  spars  and  various  materials  for  scaffolding, 
stagings,  blocking,  shores,  cribbing,  wedges,  etc.,  is  prepared. 

The  nature  of  the  work  done  in  the  other  shops  mentioned 
is  indicated  by  their  names.  In  many  of  these  shops  the 
work  done  is  similar  to  that  done  in  the  same  shops  in 
other  manufacturing  plants,  there  being  in  a  modern  ship 
much  of  the  same  equipment  that  is  found  in  buildings 
on  shore. 

4.  SHIPYARD  MACHINE  TOOLS,  ETC. 

The  principal  processes  in  the  fabrication  of  the  steel 
material  that  forms  the  hull  proper  are  as  follows: 

1.  Plate  bending  and  straightening. 

2.  Shearing. 

3.  Planing. 

4.  Punching,  drilling,  and  reaming. 

5.  Countersinking. 

6.  Flanging. 

7.  Sawing. 

8.  Forging  and  welding. 

9.  Punching  large  holes,  notches,  etc. 

10.  Cutting  with  the  oxy-acetylene  torch. 

11.  Joggling. 

12.  Hydraulic  riveting. 

13.  Frame  bending,  etc. 

14.  Furnacing  plates. 

15.  Beam  bending. 

Plate  Bending. — Certain  plates  of  a  ship — such  as  those 
at  the  turn  of  the  bilge — have  a  cylindrical  curvature. 
In  order  to  give  such  curvature  to  the  flat  plate  as  received 
in  stock  from  the  rolling  mill,  it  is  passed  through  a  large 


164 


PRACTICAL  SHIP  PRODUCTION 


machine  called  the  plate  bending  rolls,  the  essential  parts  of 
which  are  three  long  heavy  rolls  as  shown  in  section  in 
Fig.  74.  The  axis  of  the  larger  upper  roll  can  be  adjusted 
vertically  so  as  to  give,  within  reasonable  limits,  any  de- 
sired degree  of  curvature  to  the  plate.  The  length  of  the 
rolls  should  be  sufficient  to  take  the  longest  plates  that 
it  is  expected  will  ever  have  to  be  handled.  Thirty-six 


Plate 


PLATE    BENDING  ROLLS 


Punch 


Plate 


Die 


PUNCH 


COUNTERSINK 


Plate 


ANGLE  SHEAR 

PLATE  JOGGLING  MACHINE 

FIG.  74. — Operation  of  shipyard  machine  tools. 

feet  may  be  considered  as  a  fairly  great  length,  while  26 
feet  or  even  less  may  be  sufficient  for  some  yards.  The 
length  is,  of  course,  limited  by  the  difficulty  of  securing 
rolls  of  sufficient  strength,  and  the  need  for  great  length 
depends  upon  the  capacity  of  the  rolling  mills  furnishing 
the  plates. 

Plate  straightening  rolls  consist  simply  of  a  number  of 
parallel  cylindrical  rolls  through  which  a  plate  may  be 


SHIPYARDS  165 

passed  to  remove  any  unevennesses  and  make  it  perfectly 
smooth  and  flat. 

Shearing. — This  is  the  process  of  trimming  off  the  edges 
of  plates,  ends  of  bars,  etc.  It  is  accomplished  by  means 
of  a  machine  called  a  shears  which  consists  essentially  of  a 
large  shear  or  knife  that  oscillates,  as  a  rule,  vertically. 
Its  operation  is  illustrated  in  Fig.  74.  Each  stroke  cuts 
only  a  limited  portion  of  the  plate  which  must  be  moved 
along  as  the  various  strokes  are  taken.  For  shearing 
angle  bars  transversely  a  special  type  of  machine  must  be 
employed  (see  Fig.  74),  and  also  for  channels,  Z-bars,  etc., 
although  the  principle  is  the  same.  Shears,  especially 
if  slightly  dulled,  or  not  properly  aligned,  have  a  tendency 
to  tear  as  well  as  to  shear  the  material,  and  as  a  result  the 
sheared  edge  usually  has  a  slight  burr. 

Planing  consists  in  smoothening  up  the  edges  of  plates, 
shapes,  etc.,  so  as  to  remove  the  burr,  and  give  a  plane, 
flush  edge  for  purposes  of  appearance,  calking,  etc.  This 
is  accomplished  by  means  of  a  machine  called  a  plate 
planer  in  which  the  plate  or  shape  is  clamped  and  trimmed 
off  by  means  of  a  traveling  cutting  tool.  The  planer 
should  have  about  the  same  length  as  the  bending  rolls. 

Punching  is  the  process  of  putting  holes  for  rivets,  bolts, 
etc.,  in  various  plates  and  shapes.  This  is  accomplished 
by  machine  tools  similar  in  their  operation  to  shears 
(see  Fig.  74).  The  plate  or  other  piece  to  be  punched  is 
placed  upon  a  die  of  slightly  larger  diameter  than  the 
punch  which,  as  it  moves  down  with  great  force,  punches 
out  a  piece  of  metal  and  thus  forms  a  hole.  As  in  the  case 
of  shearing  a  slight  burr  is  formed  on  the  under  side  of  the 
plate  or  shape  punched  and  also,  on  account  of  the  ductility 
of  the  material,  the  hole  is  slightly  conical,  instead  of  being 
a  true  cylinder,  the  larger  diameter  being  at  the  lower 
end  of  the  hole.  It  is  to  fit  such  holes  that  the  coned 
neck  rivets  shown  in  Fig.  21  are  designed.  In  the  lowest 
sketch  in  this  figure  is  shown  the  faying  surface  between  two 
plates  riveted  together.  In  order  for  the  rivet  properly 
to  fill  the  rivet  hole  the  plates,  if  punched,  should  be 


166  PRACTICAL  SHIP  PRODUCTION 

punched  from  the  faying  surface,  so  that  the  coned  neck 
of  the  rivet  will  fit  the  cone  of  the  hole  caused  by  the 
punch. 

It  is  usually  considered  better  practice  to  have  the  rivet 
holes  true  cylinders  (in  which  case  straight  neck  rivets  are 
used),  and  with  this  object  in  view  they  are  often  drilled. 
This  is,  of  course,  more  expensive  and  takes  much  more  time 
than  punching  and  the  same  result  may  be  accomplished 
by  reaming  out  a  hole  to  the  proper  size  after  it  has  been 
first  punched  to  a  slightly  smaller  size.  A  reamer  is  a 
fluted,  revolving  spindle  tapered  at  the  end,  which  is 
inserted  into  a  hole  and  gradually  forced  further  into  it, 
the  revolving  flutes  cutting  away  some  of  the  metal  as  the 
tool  advances. 

Reaming  has  the  added  advantage  of  removing  the 
small  portion  of  material  just  around  the  hole  that  has  been 
slightly  weakened  by  the  action  of  the  punch. 

Countersinking  is  the  process  of  giving  to  one  end  of  a 
rivet  hole  a  conical  form,  a  portion  of  the  metal  being  re- 
moved, as  shown  in  Fig.  74,  by  a  revolving  tool  with  two  or 
more  cutting  edges.  This  is  done  where  countersunk  rivets 
are  to  be  driven  for  water  tightness,  or  to  be  given  a 
flush  surface.  The  countersinking  tool  is  mounted  in  a 
movable  arm  so  that  it  can  be  quickly  adjusted  to  any 
desired  location  over  the  plate  which  is  supported  on  a 
fixed  table  by  means  of  ball  rollers,  so  that  it  also  can  be 
quickly  adjusted. 

Flanging  is  the  process  of  bending  a  portion  of  a  plate 
so  as  to  give  it  a  flange  or  portion  turned  to  one  side.  This 
is  often  done  to  brackets,  etc.,  to  give  them  extra  stiffness, 
and  to  keel  plates,  garboard  plates,  etc.  (see  Fig.  75).  It  is 
accomplished  by  means  of  a  powerful  flanging  machine 
consisting  essentially  of  a  large  roller  mounted  on  heavy 
swinging  supports. 

Sawing  is  necessary  for  cutting  off  certain  heavy  shapes, 
such  as  rounds,  half  rounds  and  other  special  or  heavy  shapes 
that  cannot  be  readily  sheared.  It  is  usually  accomplished 


SHIPYARDS 


167 


by  means  of  a  special  circular  saw  designed  for  cutting 
metals. 

Forging  and  welding  is  necessary  in  fabricating  special 
parts  of  irregular  forms,  such  as  staples,  tapered  liners, 
collars,  coaming  and  other  boundary  bars,  etc.,  which  must 
be  heated  and  worked  by  hand  (see  Fig.  75). 

Punching  of  manholes,  etc.,  may  be  done  by  a  special 
powerful  hydraulic  manhole  press  which  cuts  out  a  large 
hole  in  a  plate  in  one  operation.  A  similar  operation  with  a 


Flange 


FLANGED   PLATE 


STAPLING 


Joggle- 


JOGGLED   PLATE* 


Liner - 


TAPERED  LINER 
FIG.  75. — Fabricated  parts. 

specially  shaped  punch  is  employed  for  notches  in  plates 
for  angle  bars,  etc.,  penetrating  them  at  right  angles. 

Cutting  with  the  oxy-acetylene  blow  pipe  or  torch  is  usually 
employed  instead  of  hydraulic  manhole  punching,  notch 
punching,  etc.  Irregular  holes  or  holes  of  practically 
any  desired  shape  can  be  quickly  cut  by  this  method  (see 
Chap.  VII,  Sect.  5). 

Joggling  consists  in  offsetting  the  edge  of  a  plate  or  a 
portion  of  the  length  of  a  shape  to  avoid  the  use  of  liners. 
In  Fig.  75  is  shown  a  joggled  plate,  and,  in  Fig.  74,  the 
operation  of  one  type  of  machine  that  does  the  joggling. 


168  PRACTICAL  SHIP  PRODUCTION 

Punching  and  shearing  machines  are  often  provided  with 
dies  for  joggling. 

Hydraulic  riveting  is  accomplished  by  means  of  a  heavily 
built  (and,  usually,  portable)  machine  consisting  essentially 
of  two  massive  jaws,  hinged  so  as  to  be  closed  together  by 
hydraulic  power  thus  forming  and  clenching  a  rivet  in  one 
movement. 

Frame  Bending  and  Beveling. — This  work  is  done  on  the 
bending  slabs,  previously  mentioned.  A  portion  of  a  bend- 
ing slab  is  shown  in  Fig.  78.  From  the  mould  loft  is  made  a 
template  to  which  a  piece  of  soft  iron,  known  as  a  set 
iron  is  bent.  This  is  secured  to  the  bending  slab  by  means 
of  large  dogs,  as  shown.  The  angle  bar  to  be  bent  is  first 
heated  to  a  red  heat  and  then  bent  around  the  set  iron. 
It  is  held  in  place,  as  bent,  by  other  dogs,  not  shown  in  the 
sketch.  A  tool  called  a  "moon  bar"  or  "squeezer"  is 
used  to  force  the  bar  around  where  the  curvature  is  greatest. 
While  the  frame  bar  is  still  hot  it  is  beveled  by  having  the 
angle  between  its  two  flanges  opened  or  closed  to  the  proper 
amount  at  each  point  of  its  length.  This  is  done  by  means 
of  a  special  tool  (a  beveling  lever)  with  a  wrench-like 
jaw  that  can  be  fitted  over  the  vertical  flange,  or  by  a  few 
light  blows  of  the  sledge  hammer  (see  Fig.  79).  The  other 
flange,  during  this  operation  is  secured  fast  to  the  bending 
slab  by  dogs. 

Furnacing  of  Plates. — Certain  plates  of  the  shell  plating 
are  undevelopable,  as  for  example  the  boss  and  oxter  plates. 
Special  molds  have  to  be  made  for  these,  built  up  of  light 
wood  to  the  actual  form  of  the  ship,  from  which  heavy 
metal  beds  are  made,  of  plates  and  angles,  in  which  the 
plates  after  having  been  heated  red  hot  are  laid  and  ham- 
mered into  shape.  Such  furnaced  plates  are  made  slightly 
thicker  than  would  otherwise  be  necessary  in  order  to  com- 
pensate for  possible  loss  in  thickness  and  strength  caused 
by  the  furnacing  and  shaping. 

In  the  preceding  paragraphs  have  been  described  the 
more  important  processes  in  ship  construction  that  require 
the  use  of  machine  tools,  and  the  tools  most  commonly 


SHIPYARDS  169 

used  have  been  mentioned.  Some  of  these  tools  are  abso- 
lutely essential  to  shipbuilding  work,  while  others  may  be 
dispensed  with  and  their  functions  performed,  though  in  a 
less  efficient  manner,  by  the  others.  The  exact  equipment 
necessary  for  any  given  shipyard  is  difficult  to  determine 
and  varies  with  the  size  of  the  yard,  the  capital  available, 
the  type  of  ships  to  be  built,  etc. 

The  following  may  be  considered  as  a  proper  equipment 
for  a  first-class  yard  of  moderate  size: 

Bending  rolls  (1  large;  1  or  2  small). 

Plate  mangles  or  straighteners  (2). 

Plate  planers  (2  or  3). 

Punches  (6  or  8). 

Shears  (6  or  8). 

Angle  and  other  special  shears  (3  or  4). 

Flanging  machine. 

Joggling  rolls. 

Hydraulic  press. 

Radial  drilling  and  countersinking  spindles  (6  or  8). 

Steam  hammers  (several). 

Hydraulic  riveting  machines  (2  or  3). 

Bending  slabs. 

Plate  furnaces  (2  or  3). 

Angle  furnaces  (2  or  3) . 

Beam  press. 

Scarphing  machine. 

The  above  applies  only  to  the  larger  machine  tools  used 
primarily  for  hull  construction  and  takes  no  account  of  a 
great  variety  of  miscellaneous  small  portable  tools  and 
machines,  or  of  tools  in  the  woodworking-,  plumbers-, 
machine-,  smith-,  and  other  auxiliary  shops. 

5.  PERSONNEL  OF  A  SHIPYARD 

The  organization  of  a  shipyard  is  commonly  based  upon 
a  division  of  the  work  into  two  main  parts :  that  pertaining 
to  the  hull,  and  that  pertaining  to  the  machinery.  The 
plans  for  the  hull  and  its  fittings  and  equipment,  when 
required  to  be  made  in  the  yard,  are  prepared  by  a  staff 
of  designers  and  draftsmen  entirely  separate  and  distinct 


170  PRACTICAL  SHIP  PRODUCTION 

from  those  preparing  the  plans  for  the  engines,  boilers, 
auxiliaries,  etc.  Similarly  the  work  of  manufacturing, 
erecting,  testing  and  installing  the  machinery  is  largely 
done  by  a  different  force  of  mechanics  from  those  who  build 
the  hull  and  make  and  install  its  fittings. 

Considering  the  shipbuilding  or  hull  end,  there  will  be 
found  in  a  well-equipped  shipyard,  workers  in  the  following 
occupations  and  trades :  designers  and  draftsmen,  loftsmen, 
layers-out,  workers  in  the  plate  and  angle  and  fabricating 
shops,  frame  benders,  anglesmiths,  furnacemen,  shipfitters, 
erectors,  laborers,  bolters-up,  etc.,  drillers,  reamers,  riveters, 
holders-on,  heaters,  passers,  chippers  and  calkers,  testers, 
shipwrights  or  ship  carpenters,  joiners,  plumbers,  pipe- 
fitters, shipsmiths,  drop  forgers,  heavy  forgers,  sailmakers, 
riggers,  sheet-metal  workers,  machinists,  wood  calkers, 
coppersmiths,  galvanizers,  pattern  makers,  molders,  melt- 
ers,  chippers  and  other  foundry  workers,  painters,  and  var- 
nishers,  masons,  electricians,  boat  builders,  not  to  mention 
all  of  the  miscellaneous  auxiliary  trades,  such  as  janitors, 
watchmen,  laborers,  helpers,  drivers,  teamsters,  chauffeurs, 
crane  men,  firemen,  locomotive  engineers,  etc. 

Workmen  of  each  of  the  skilled  trades  all  have  helpers 
to  assist  them  and  in  each  of  these  trades  there  are  one  or 
more  foremen  or  "  bosses, "  and  various  sub-foremen  or 
supervisors,  ranging  from  the  bosses  down  through  assist- 
ant-bosses, quartermen,  leadingmen,  etc.,  to  " snappers" 
each  of  whom  is  in  charge  of  a  certain  group  or  unit  of 
mechanics. 

Designers  and  Draftsmen. — These  are  the  men  who 
make  the  necessary  calculations,  draw  the  plans,  and  pre- 
pare the  specifications  from  which  the  ship  is  to  be  built. 
They  should  have  both  practical  and  theoretical  knowl- 
edge of  naval  architecture  especially  the  latter,  since 
upon  a  correct  knowledge  of  the  theoretical  principles 
governing  the  design  of  a  ship  depends  the  success  of  the 
ship.  No  matter  how  well  she  may  be  built,  a  poorly 
designed  ship  may  be  of  little  practical  value  and  may  even- 
be  a  source  of  great  danger. 


SHIPYARDS  171 

Loftsmen. — The  loftsmen  are  the  men  who  take  the  plans 
of  the  ship  as  furnished  by  the  draftsmen,  and  by  laying 
them  down  to  full  scale  on  the  mold  loft  floor,  make  tem- 
plates from  which  the  material  that  is  to  form  the  hull  can 
be  marked  out  and  fabricated.  Their  work  requires 
much  of  the  same  knowledge  that  is  essential  for  draftsmen, 
and  in  addition  a  considerable  amount  of  practical  expe- 
rience with  shop  and  yard  practices. 

Layers -out. — From  the  templates  furnished  by  the 
loftsmen  various  plates  and  shapes  must  be  laid  out  for 
shearing,  planing,  punching,  bending,  flanging,  beveling, 
rolling,  etc.  This  work  is  done  by  layers-out  who  are 
usually  possessed  of  the  same  qualifications  as  shipfitters. 
Their  work,  however,  is  confined  to  the  laying-out  shop, 
whereas  shipfitters  usually  do  their  work  largely  on  the 
ship.  (See  under  Shipfitters,  below.) 

Workers  in  the  Plate  and  Angle  Shops. — After  the 
material  has  been  laid  out  it  is  sent  to  the  various  machine 
tools  where  the  necessary  punching,  shearing,  planing, 
countersinking,  etc.,  is  done.  A  considerable  variety  of 
workers  operate  these  tools,  although  usually  the  work  is 
such  that  men  capable  of  operating  one  tool  can  also  oper- 
ate several  others.  Among  the  trades  engaged  in  this  work 
the  following  are  found:  manglers  or  plate  straighteners, 
drillers,  jogglers,  punch  and  shear  operators,  plate  rollers, 
countersinkers,  acetylene  cutters — although  not  always 
called  by  these  names.  The  operations  at  most  of  these 
machine  tools  consist  in  guiding  the  plates  or  shapes,  sup- 
ported by  various  types  of  cranes  and  hoists,  into  position, 
and  then  pulling  the  necessary  lever  or  making  the  neces- 
sary electric  contact  to  cause  the  machine  to  perform  its 
function  in  each  case.  The  quality  of  work  and  the  speed 
with  which  it  is  done  is  largely  dependent  upon  the  skill  of 
the  workman.  This  skill  can  be  gained  only  by  experience. 

Frame  Benders,  Anglesmiths,  Furnacemen,  Etc.— 
These  and  similar  names  apply  to  the  workmen  who  do 
the  working  of  plates  and  shapes  to  special  forms  that 
must  be  done  with  the  material  red  hot.  All  of  this  work 


172  PRACTICAL  SHIP  PRODUCTION 

partakes  of  the  nature  of  blacksmith  work.  The  greater 
part  consists  in  bending  and  beveling  frame  and  reverse 
frame  bars,  making  staples,  collars,  coaming  angles,  shaping 
special  plates  of  the  shell,  etc.  It  is  evident  that  such 
work  can  be  done  properly  only  by  men  of  good  phy- 
sique, and  skill,  that  is  obtained  only  as  the  result  of  long 
experience. 

Shipfitters. — The  shipfitting  trade  is  the  one  metal 
worker's  trade  most  closely  associated  with  shipbuilding. 
The  shipfitter,  with  modern  steel  vessels,  corresponds  to 
the  shipwright  with  the  old  wooden  ships.  In  general, 
the  duties  of  a  shipfitter  are  to  lay  out  or  fit  the  various 
members  of  the  ship's  hull. 

It  will  be  noted  that  a  large  amount  of  the  material  that 
enters  into  the  hull  of  a  steel  ship  is  laid  out  and  fabricated 
from  templates  furnished  by  the  mold  loft.  The  laying 
out  of  all  steel  material  not  so  handled  is,  in  general,  the 
province  of  the  shipfitter.  It  is,  of  course,  possible  by 
following  carefully  prepared  plans,  and  requiring  the  most 
careful  and  accurate  workmanship,  to  get  out,  in  advance, 
in  the  shops,  all  the  parts  of  a  ship.  In  some  shipyards 
this  method  is  very  closely  approached,  but  in  practice  it 
is  found  to  be  very  difficult  to  fabricate  all  parts  in  ad- 
vance so  that  they  will  fit  together  properly  when  as- 
sembled. Therefore  it  is  usual  to  fabricate  a  certain 
amount  of  material  from  templates  and  plans,  but  to  leave 
a  certain  remainder  to  be  made  specially  from  templates 
prepared  by  shipfitters  to  fit  other  parts  after  these  other 
parts  are  in  place  in  the  ship.  For  example,  after  the 
frames  have  been  erected  certain  plates  of  the  shell  are 
usually  laid  out  from  templates  actually  " lifted"  or  made 
in  place  on  the  portion  of  the  frames  that  is  to  be  occupied 
by  those  particular  plates.  The  edges  of  the  plates  and 
the  exact  positions  and  sizes  of  the  rivet  holes  in  each 
case  can  thus  be  transferred  directly  to  the  template  from 
the  work  on  which  the  plate  for  which  the  template  is 
made  is  to  fit.  Such  a  template  consists  of  thin  strips  of 
soft  wood,  nailed  or  tacked  together  to  form  a  skeleton 


SHIPYARDS  173 

" pattern"  of  the  plate,  on  which  is  marked  all  information 
necessary  for  fabricating  the  plate. 

Occasionally,  in  the  case  of  lighter  members,  it  is  found 
convenient  and  advisable  to  place  the  steel  material  itself 
in  position  in  the  ship,  mark  it  off,  and  send  it  then  to  the 
shop  for  fabrication.  In  other  cases  the  steel  material 
may  be  laid  off  directly  by  the  shipfitter  from  a  plan- 
without  the  use  of  a  template.  Some  of  the  men  skilled 
in  ship  fitting  work  are  usually  assigned  to  duty  as  "  layers- 
out,"  marking  off  the  plates  and  shapes  for  fabrication  from 
mold  loft  templates. 

The  shipfitter' s  trade  is  one  calling  for  both  skill  and 
intelligence,  combined  with  a  certain  amount  of  practical 
mathematical  knowledge  and  an  ability  to  "read"  plans. 
Shipfitters  are  more  or  less  concerned  with  the  production 
of  practically  all  the  main  structural  members  of  the  hull. 
Some  of  the  simpler  parts  which  are  usually  laid  out  by 
the  shipfitters  (or  fitters-up  as  they  are  sometimes  called) 
are  described  below,  in  order  to  show,  concretely,  what 
their  duties  are,  even  although  some  of  these  parts  have 
been  previously  referred  to.  These  are  illustrated  in 
Fig.  76. 

A  bosom  piece  is  a  short  section  of  angle  bar  used  to  con- 
nect the  ends  of  two  other  angle  bars  that  butt  together. 
The  heel  of  the  bosom  piece  is  planed  off  to  fit  into  the 
bosom  of  the  other  two  bars  and  the  toes  of  the  bosom 
piece  are  planed  off  so  as  not  to  project  beyond  the  toes 
of  the  bars,  as  shown. 

A  clip  is  simply  a  short  piece  of  angle  bar  used  to  connect 
two  other  parts  at  right  angles,  or  nearly  so,  as  shown 
in  the  figure. 

A  bracket  is  a  flat  plate,  usually  of  triangular  shape  used 
to  tie  together  and  stiffen  two  plates  or  other  flat  members 
meeting  at  an  angle.  In  Fig.  76  is  shown  a  bracket  flanged 
on  its  edge,  for  additional  stiffness,  and  having  a  lightening 
hole  in  it,  to  save  weight,  connecting  two  plates  that  are 
at  right  angles  to  each  other. 

A  butt-strap  (see  Fig.  76)  is  a  piece  of  plate  used  to  con- 


174 


PRACTICAL  SHIP  PRODUCTION 


nect  two  plates  that  butt  against  each  other.  The  butt- 
strap  makes  a  lap-joint  with  each  plate.  Sometimes  a 
butt-strap  is  fitted  on  each  side  of  the  two  plates,  in  which 
case  the  straps  are  called  double  butt-straps.  According 
to  the  number  of  rows  of  rivets  butt-straps  are  called 


Toe  planed  off 


Bosom  Piece — t 


^xButt  of  Angles 


Heel  planed  off 


BOSOM   PIECE 


CLIP  CONNECTING  TWO  PLATES 


©    ©]©    © 

1 

©    ©  1  ©   © 

©    ©';©   © 

t 

©  v©  j  ©   © 

, 

^ 

late      V-ButtStraP        \ 
late      , 

/—\  fr~\    /~s     /~^ 

&xsm  mAmavz 

i/ 

YSf/YSSSSSSL 

FLANGED   BRACKET 
(riveting  omitted ) 


BUTT  STRAP 


TAPERED   LINER 
(riveting  omitted) 
FIG.  76. — Shipfitting  work. 


— Liner 


single-riveted,   double-riveted,   treble  riveted,   etc.     The   one 
shown  in  Fig.  76  is  a  single,  double-riveted  butt-strap. 

Liners  are  strips  of  plating  fitted  between  frames,  beams, 
etc.,  and  the  plating  laid  on  them  to  bring  the  plating 
flush  with  other  plating  over  which  it  laps.  Liners  may  be 


SHIPYARDS  175 

either  straight  or  tapered.  In  Fig.  76  is  shown  a  tapered 
liner. 

The  sketches  just  described  will  serve  to  indicate  the 
character  of  the  work  done  by  shipfitters,  these  being, 
however,  some  of  the  simpler  parts  laid  out  by  this  trade. 

Erectors,  Laborers,  Bolters-up,  Riggers,  Etc. — After  the 
various  members  of  the  ship's  hull  have  been  fabricated 
they  are  transported  to  the  building  slip,  hoisted  into  place 
by  cranes  or  erected  by  hand  and  bolted  in  place,  the  bolts 
being  inserted  through  rivet  holes  to  secure  the  parts  for 
riveting.  Only  a  portion  of  the  rivet  holes  need  to 
be  so  filled,  the  rest  being  left  empty.  The  workmen  who 
do  this  work  are  variously  called  riggers,  laborers,  helpers, 
bolters-up,  regulators,  erectors,  etc.  In  order  to  make  the 
various  parts  fit  it  is  sometimes  necessary  to  draw  them 
together  so  that  the  rivet  holes  overlap  exactly,  or  are  fair. 
This  is  done  by  means  of  a  small  tapered  pin,  called  a 
drift  pin  which  is  driven  into  the  rivet  holes  until  they  are  in 
line  (see  Fig.  81).  Excessive  use  of  the  drift  pin  is  an 
evidence  of  poor  workmanship  and  should  not  be  tolerated. 

The  bolts  are  saved  after  they  have  served  their  purpose 
and  used  over  and  over  again,  and,  as  the  lengths  vary,  it 
is  customary  to  have  on  hand  a  large  number  of  washers, 
made  by  punching  holes  in  small  rectangular  pieces  of 
plate,  for  use  with  these  bolts  to  save  labor  in  screwing  up 
the  nuts. 

Drillers  and  Reamers. — After  the  hull  members  have  been 
bolted  up  in  place  it  is  usually  necessary  to  drill  certain 
rivet  holes  that  it  is  not  practicable  to  have  punched  before 
erection,  and  to  ream  out  the  holes  that  have  been  punched, 
in  order  to  give  smooth,  fair  holes  suitable  for  the  riveting. 
This  work  is  done  by  the  drillers  and  reamers.  Drillers 
also  are  employed  to  tap  certain  holes  designed  for  bolts 
or  tap-rivets. 

Riveters,  Holders -on,  Heaters,  Passers. — The  drillers 
and  reamers  are  followed  by  the  riveters,  who  drive  the 
rivets  that  form  the  fastenings  of  the  various  members. 
Riveting  may  be  done  either  by  hand  or  by  pneumatic 


176  PRACTICAL  SHIP  PRODUCTION 

hammers,  the  use  of  the  latter  now  being  the  most  common 
practice.  A  riveter  works  in  a  gang,  which  consists, 
besides  himself,  of  a  holder-on,  heater-boy,  and  one  or  more 
rivet-passers.  The  heater  boy  places  the  cold  rivets  in  a 
small  portable  forge  in  which  they  are  heated  to  a  cherry 
red.  They  are  removed  from  the  forge  as  needed,  and 
taken  by  the  passer  (or  passers)  to  the  holder-on  who 
inserts  each  rivet  in  the  proper  hole,  after  removing  a  bolt, 
if  necessary,  from  the  opposite  end  to  that  at  which  the 
riveter  stands.  The  holder-on  then  shoves  the  rivet  into  the 
hole  until  the  head  takes  up  well  against  the  plate  or  shape 
and  holds  it  there  with  a  heavy  holding-on  hammer  or  dolly- 
bar.  The  riveter  then  drives  the  point  of  the  rivet  against 
the  other  side  of  the  members  to  be  connected,  flattening 
it  out  and  clinching  it  so  as  completely  to  fill  the  rivet  hole. 
This  work  must  be  done  while  the  rivet  is  hot.  Riveting 
requires  considerable  skill  and  great  strength  and  endur- 
ance. 

Calkers,  Chippers,  and  Testers. — All  plated  surfaces  that 
form  boundaries  of  compartments  into,  or  from  which 
water,  oil,  etc.,  must  not  leak,  require  calking.  This 
consists  in  tightly  closing  the  joints  between  the  connecting 
parts  through  which  leakage  might  occur.  As  in  the  case 
of  riveting,  calking  may  be  done  either  by  hand  or  pneu- 
matic tools — the  tools  in  the  case  of  calking,  however, 
being  chisels  instead  of  hammers.  These  tools  are  used  to 
force  the  steel  material  of  one  part  against  the  surface  of  the 
adjoining  part.  This  work  is  done  by  the  calkers  who  also 
are  employed  at  times  to  do  chipping  which  consists  in  the 
use  of  chisels,  to  trim  edges,  cut  holes,  etc.,  the  same  pneu- 
matic hammer  being  used  as  for  calking,  but  with  a  differ- 
ent tool.  These  workmen  are  therefore  often  called 
chippers  and  calkers.  After  the  calking  is  completed 
the  tightness  of  the  joints  is  tested  by  filling  the  compart- 
ment with  water  or  compressed  air,  and  any  leaks  thus 
discovered  are  made  good.  This  testing  is  also  usually 
done  by  the  chippers  and  calkers,  who  are  therefore  some- 
times called  testers. 


SHIPYARDS  177 

The  draftsmen,  loftsmen,  layers  out,  fabricating  shop 
workers,  shipfitters,  erectors,  drillers,  riveters  and  calkers 
comprise  those  workers  who  are  intimately  connected  with 
the  building  of  the  hull  proper  of  a  steel  ship.  The  follow- 
ing trades,  however,  also  have  considerable  to  do  with 
shipbuilding  : 

Shipwrights  (or  Ship  Carpenters). — Who  prepare  keel 
blocks,  wedges,  shores,  staging,  launching  ways,  scaffold- 
ing, ribbands,  etc. — the  auxiliary  wood  work  in  connection 
with  building  the  ship — and  make  and  install  wood  decks, 
masts,  spars,  foundations,  etc. 

Joiners — who  make  and  install  the  lighter  wooden  parts 
of  the  ship,  such  as  wooden  doors,  partitions,  windows, 
stairways,  lockers,  cold  storage  compartments,  shelving, 
bulletin  boards,  furniture,  etc. 

Plumbers  and  pipe  fitters — who  do  work  on  the  various 
plumbing  and  piping  systems  of  the  ship. 

Shipsmiths  and  heavy,  and  drop -forgers — who  fashion 
the  various  fittings  and  other  parts  required  to  be  heated 
and  hammered  in  the  smith  shop. 

Sailmakers — who  manufacture  the  sails,  awnings,  etc. 

Riggers — who  make  and  fit  the  necessary  rigging  for  the 
masts,  spars,  etc.  (Not  the  same  as  the  riggers  who  assist 
in  erecting  the  parts  of  the  hull). 

Sheet  metal  workers — who  roanufacture  ventilation 
ducts,  metal  lockers,  wire  mesh  partitions,  sheet  metal, 
sheathing,  etc. 

Hull  machinists — who  do  the  necessary  fitting  and  in- 
stalling of  steering  gears,  hull  valves  and  zincs,  operating 
gears,  etc.,  etc. — as  distinguished  from  the  machinists  who 
are  employed  on  the  main  engines  and  auxiliaries. 

Wood  calkers — who  calk  the  seams  of  wood  decks  and 
planking. 

Coppersmiths — who  make  copper  pipes,  kettles  and  other 
fittings. 

Galvanizers — who  galvanize  or  coat  with  zinc  the  outside 
surfaces  of  various  steel  and  iron  parts  exposed  to  the 
weather. 

12 


178  PRACTICAL  SHIP  PRODUCTION 

Pattern  makers — who  make  wooden  patterns  from  which 
castings  can  be  made. 

Holders,  melters  and  other  workers  in  the  foundry,  where 
the  castings  are  made. 

Painters  and  varnishers — who  have  considerable  work 
to  do  both  on  the  ships  and  in  their  shop.  The  painters 
usually  are  the  workmen  who  apply  bituminous  com- 
positions. 

Masons — who  install  tiling  in  bath  rooms,  lavatories, 
galleys,  laundries,  etc.,  and  apply  portland  cement  in 
various  out  of  the  way  pockets  and  other  inaccessible 
parts  of  the  hull. 

Electricians — who  install  wiring  and  electrical  equipment. 

Boatbuilders — who  make  the  boats  that  go  with  the 
ships. 

6.  MANAGEMENT 

Given  a  shipyard,  with  building  slips  prepared,  shops, 
tools  and  other  yard  equipment  complete,  plans  and 
specifications  at  hand,  in  order  to  produce  ships  efficiently 
there  must  be  a,  management,  organized  for  guiding,  direct- 
ing, and  controlling  the  workmen,  ordering  the  necessary 
materials,  co-ordinating  the  work,  etc.,  etc. 

The  great  factor  in  the  expeditious  and  economical 
production  of  ships  (as  in  all  manufacturing  enterprises) 
is  management.  The  function  of  the  management  is  to 
do  the  thinking  necessary  in  order  that  the  construction 
of  the  ships  may  proceed  smoothly  and  expeditiously.  The 
building  of  a  ship  may  be  divided  into  a  great  many  elemen- 
tary tasks.  In  the  final  analysis  each  of  these  tasks  repre- 
sents manual  work  that  must  be  done  by  some  particular 
workman  or  group  of  workmen.  If  it  be  assumed  that  these 
workmen  have  the  skill,  experience  and  physical  condition 
requisite  for  the  performance  of  their  individual  tasks, 
then  the  problem  of  the  management  becomes  one  of  seeing 
that  each  and  every  one  of  these  workmen  is  given  working 
conditions  that  will  permit  of  his  work  being  done  quickly 
and  efficiently. 


SHIPYARDS  179 

In  order  that  such  conditions  may  exist  the  following 
points  must  be  looked  out  for: 

(a)  Plans. — The  necessary  plans  and  instructions  must 
be  at  hand  in  order  that  the  workman  will  have  no  doubt 
as  to  just  what  he  is  expected  to  do,  and  how  it  should  be 
done. 

(b)  Material. — Material  required  for  each  task  must  be 
ready  at  the  time  that  it  is  needed,  and  it  must  be  of  suitable 
quality  and  furnished  in  sufficient  quantity. 

(c)  Tools. — The  workman  must  be  furnished  with  all 
necessary  tools,  and  these  must  be  kept  at  all  times  in 
satisfactory  operating  condition. 

(d)  Working  Conditions. — In  order  for  the  workman  to 
do  his  work  properly  he  must  have  good  light,  ventilation, 
protection  from  the  weather,  etc.     If  he  is  using  tools 
operated  by  compressed  air  suitable  connections  to  the 
air  supply  must  be  provided.     If  he  is  working  at  night 
special  electric  lights  must  be  rigged. 

The  various  problems  to  be  solved  in  seeing  that  these 
four  points  are  looked  out  for  are  much  more  difficult 
than  would  be  thought  at  first  sight,  and  the  manner  in 
which  these  problems  are  met  will  have  a  very  important 
bearing  on  the  efficiency  of  the  shipyard  as  a  whole. 


CHAPTER  VI 
PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION 

From  the  time  that  it  is  decided  to  build  a  ship,  even 
from  plans  already  completed,  up  to  the  time  when  the  keel 
is  laid,  and  the  work  of  actually  building  the  hull  is  com- 
menced, there  is  always  a  considerable  interval.  In  many 
cases  a  large  proportion  of  the  work  is  done  before  a  single 
piece  is  erected  on  the  building  slip,  the  keel-laying  being 
postponed  as  long  as  possible,  in  order  that  sufficient 
fabricated  material  may  be  on  hand  to  permit  the  work  of 
erection,  when  once  started,  to  proceed  rapidly.  In  every 
case  a  certain  amount  of  preliminary  work  must  be  done 
before  the  building  of  the  hull  can  be  commenced. 

Few  yards  carry  a  stock  of  materials  so  large  that  at 
least  some  new  stock  does  not  have  to  be  ordered  when  it  is 
proposed  to  build  a  new  ship.  Unless  the  new  ship  is  a 
duplicate  of  another  previously  built  by  the  yard,  and  for 
which  the  molds  and  templates  have  been  saved,  a  large 
amount  of  mold-loft  work  must  first  be  done.  In  every 
case  the  material  must  be  fabricated  or  made  ready  for 
erection.  The  preliminary  steps  in  ship  construction  are 
therefore : 

1.  Ordering  the  material. 

2.  Making  the  molds,  templates,  patterns,  etc. 

3.  Fabrication  of  the  material. 

1.  ORDERING  THE  MATERIAL 

Assuming  that  the  shipbuilder  has  been  furnished  with 
complete  plans  and  specifications  of  the  ship  (or  ships) 
that  he  is  to  build,  the  first  step  in  the  production  of  the 
ship  is  the  ordering  of  the  material.  This  usually  includes 
a  great  many  miscellaneous  fittings  and  auxiliaries  which 

180 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION      181 

are  usually  delivered  complete  and  ready  for  installation, 
and  the  type  and  quality  of  which  are  covered  by  the  speci- 
fications—sometimes exactly  and  sometimes  somewhat 
loosely — but  the  principal  material  to  be  ordered  is  the  steel 
for  the  hull. 

In  ordering  castings  and  forgings  to  be  made  by  other 
concerns,  complete  working  plans  must  be  furnished  with 
the  order,  showing  exactly  what  is  desired. 

The  plates  and  shapes  present  the  greatest  difficulty 
since  the  sizes  of  each  must  be  so  specified  as  to  allow  for 
shaping  and  cutting  to  the  proper  finished  size  (which 
usually  cannot  be  foretold  with  complete  accuracy)  while 
at  the  same  time  not  allowing  so  much  excess  as  to  cause 
a  serious  waste  of  material. 

The  shell  plates,  keel,  stringers,  keelsons,  etc.,  are  usually 
ordered  from  a  wooden  model,  made  to  scale,  on  which 
these  various  parts  are  laid  off  accurately  in  ink.  This  is 
necessary  since  a  ship's  form  is  an  undevelopable  surface 
so  that  the  plates  cannot  readily  be  shown  in  their  true 
form  in  the  plans.  A  certain  margin  of  material  must  be 
ordered  to  allow  for  stretching,  shrinkage  and  change  of 
form  due  to  working  the  plates  to  the  proper  form  and 
size.  This  depends  upon  the  experience  of  the  person 
making  up  the  order  and  the  general  quality  of  work- 
manship of  the  yard. 

Frames,  reverse  frames  and  other  similar  parts  that  have 
to  be  bent  are  girthed  from  the  plans — a  certain  number 
being  thus  actually  measured  and  the  girths  of  the  inter- 
mediate ones  being  obtained  by  plotting  curves  through 
the  points  thus  obtained.  In  bending,  frames  usually 
stretch  slightly  at  the  heel  so  that  little  if  any  allowance  in 
excess  of  the  girthed  length  has  to  be  made.  For  deep 
members  to  be  bent  the  girth  should  be  taken  along  the 
neutral  line. 

The  material  is  usually  ordered  direct  from  the  various 
structural  plans,  material  schedules  being  prepared  by  the 
draftsmen,  but  if  time  permits,  or  if  the  templates  are 
already  at  hand  as  in  the  case  of  a  number  of  ships  being 


182  PRACTICAL  SHIP  PRODUCTION 

built  from  the  same  plans,  a  certain  saving  can  be  made  by 
making  up  the  material  schedule  from  the  full  size  templates, 
since  the  percentage  of  error  is  then  less.  The  amount  of 
scrap  from  hull  material — or  the  difference  between  the 
weight  as  ordered  and  as  worked  into  the  ship — is  usually 
about  10  percent  of  the  total. 

Great  care  must,  of  course,  be  exercised  in  ordering  ma- 
terial to  see  that  all  parts  are  considered  and  nothing  over- 
looked in  making  up  the  order.  It  is  also  important  to 
consider  the  times  of  delivery,  and  to  see  that  orders  are 
so  placed  that  the  various  deliveries  will  be  made  before 
they  are  actually  needed.  Materials  for  keel,  keelsons, 
bottom  plating,  and  inner  bottom  framing  will,  of  course, 
be  needed  before  frames,  deck  beams,  etc.  Little  is  gained 
by  having  anchors  arrive  before  stem  and  stern  castings. 

2.  MOLDS,  TEMPLATES,  PATTERNS,  ETC. 

As  soon  as  the  plans  of  the  ship  are  completed  the  work 
of  making  molds,  patterns,  etc.,  may  start,  even  in  advance 
of  the  receipt  of  any  structural  material.  Plans  for  castings 
are  sent  to  the  pattern  shop  for  use  in  making  the  necessary 
patterns,  or  to  the  outside  concerns  from  whom  the  castings 
may  be  ordered. 

In  the  mold  loft  the  lines  of  the  ship  are  drawn  on  the 
floor  to  full  size  either  with  chalk  or  with  lead  pencil.  For 
this  purpose  long  flexible  strips  of  wood,  called  battens, 
are  used  which  are  held  in  place  by  large  flat  headed  nails 
with  very  sharp  points.  The  ordinates  for  the  various 
curves  are  furnished  in  the  form  of  tables  of  offsets,  each 
ordinate,  or  offset,  being  given  in  feet,  inches  and  eighths  of 
inches.  For  example,  the  offset  19-7-6  means  19  ft.  7%'' \ 
Owing  to  the  difficulty  of  obtaining  exact  accuracy  in  the 
plans  it  is  usually  found  necessary  to  make  numerous 
changes  in  fairing  up  the  lines  on  the  floor  of  the  loft.  After 
this  has  been  done  a  revised  table  of  mold-loft  offsets  is  made 
for  record  and  possible  future  use.  In  the  lines  as  laid 
down  in  the  mold  loft  appears  every  frame,  these  being, 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION     183 

of  course,  much  more  closely  spaced  than  the  frame  stations 
used  in  drawing  the  lines  in  the  drafting  room. 

The  work  of  laying  down  and  fairing  up  the  lines  on  the 
mold  loft  floor  is  the  same  as  that  of  the  draftsman  who 
made  the  plan  of  the  lines,  except  that  it  is  done  on  a  large 
scale.  It  is,  in  brief,  nothing  more  nor  less  than  putting 
into  practice  the  principles  of  descriptive  geometry.  The 
various  details  of  this  work  form  a  study  in  themselves,  and 
for  a  complete  treatment  of  these  matters  the  reader  is 
referred  to  text  books  on  the  subject — such  as,  for  in- 
stance, Watson's  " Naval  Architecture."  Loftsmen  ac- 
quire their  skill  only  as  the  result  not  only  of  study  but 
also  of  actual  experience  in  the  loft. 

After  the  lines  have  been  faired  the  scrieve  board  is  made. 
This  consists  of  a  special  section  of  wood  flooring  (often 
made  in  sections,  and  portable)  of  sufficient  size  to  take 
the  full  size  body  plan  of  the  ship.  On  this  flooring  is 
drawn  the  complete  body  plan — showing  every  frame, 
together  with  inner  bottom,  decks,  stringers,  keel,  keelsons, 
longitudinals,  margin  plates,  plate  laps,  lines  of  ribbands 
and  such  other  information  as  is  necessary  for  the  fabrica- 
tion of  the  various  members.  All  of  these  lines  are  cut 
into  the  surface  of  the  scrieve  board  by  means  of  a  sharp, 
V-shaped  tool,  called  a  scrieve-knife.  This  is  done  to 
prevent  their  being  obliterated  by  the  rough  usage  to  which 
this  board  is  subjected  during  the  processes  of  making 
molds,  templates,  etc. 

The  scrieve  board  is  used  for  making  the  various  molds 
of  frames,  beams,  floor  plates,  etc.,  etc.  These  are  usually 
made  of  strips  of  thin  soft  wood  tacked  together,  and  shaped 
to  the  form  of  the  particular  members  that  they  represent. 
The  terms  mold  and  template  are  often  used  synonymously 
but  the  first  applies  strictly  to  shape,  whereas  a  template 
in  addition  to  having  the  form  of  the  part  also  has  marked 
upon  it  certain  information,  such  as  locations  of  rivet 
holes,  edges  to  be  sheared  or  planed,  lightening  holes,  coun- 
tersinking, etc.  Some  templates  are  made  of  paper  instead 
of  wood,  or  even  in  some  cases  of  light  metal.  Templates 


184 


PRACTICAL  SHIP  PRODUCTION 


that  are  to  be  used  repeatedly  are  made  more  substantially 
than  those  that  are  to  be  used  only  once.  Molds  for 
furnaced  plates  that  have  curvature  in  three  dimensions 
are  built  up  specially  of  more  substantial  wooden  pieces. 


oooooooo 
oo  oooooo 


OO  O  O  O.'-O  O  O  O 


FRAME  MOLD 


TEMPLATE   FOR  SHELL  PLATE 


FIG.  77. — Template  and  mold. 

Figure  77  shows  a  template  for  a  shell  plate  and  (to  a 
smaller  scale)  a  mold  for  a  frame — both  made  of  strips  of 
batten  wood  tacked  together. 

The  laying  off  and  fairing  of  the  lines  on  the  mold  loft 
floor  and  the  construction  of  the  molds  and  templates  for 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION     185 

the  hull  material  that  is  to  be  fabricated  in  advance  con- 
stitute the  principal  work  of  the  loftsmen. 

In  addition  to  this  various  battens  are  marked  off  giving 
certain  dimensions  and  other  information  for  use  by  the 
workmen  in  the  fabricating  shops.  Bevel  boards  are  also 
made  by  the  loftsmen.  These  are  small  strips  of  batten 
wood  on  which  are  drawn  lines  which  indicate  the  angle 
of  bevel  for  each  frame  at  certain  fixed  points  along  its 
girth.  The  obtaining  of  these  bevels  is  accomplished  by 
measuring  on  the  scrieve  board  the  distance  between  ad- 
jacent frame  curves,  taken  normal  to  their  curvature,  and 
combining  it  with  the  fixed  distance  fore  and  aft  between 
frames  (or  the  frame  spacing)  so  as  to  determine  the  angle 
of  the  small  right  angled  triangle  thus  formed  between  each 
pair  of  adjacent  frames.  In  order  to  give  all  frames  an 
open  bevel  the  bosoms  of  the  forward  frames  "look"  aft  and 
of  the  aft  frames  look  forward. 

3.  FABRICATION  OF  HULL  MATERIAL 

Fabrication  is  the  term  applied  to  the  various  processes 
by  which  the  raw  material  as  received  from  the  steel  mills 
is  laid  off  and  fashioned  so  that  it  is  formed  into  the  various 
structural  members  of  the  hull,  which,  when  erected,  will 
fit  together  properly  with  their  neighboring  parts.  Such 
parts  of  the  hull  as  are  ordered  specially,  or  made  in  the 
yard,  as  forgings  or  castings  require  no  special  description, 
as  the  methods  of  making  ship  forgings  and  castings  are 
no  different  from  those  of  making  such  pieces  for  other 
purposes.  Such  finishing  of  these  parts  as  is  required  is 
done  after  receipt  of  the  rough  castings  either  by  machine 
or  by  chipping  with  hand  or  pneumatic  chipping  tools. 
The  fabrication  of  the  following  parts  is  more  or  less  pe- 
culiar to  shipbuilding  and  will  be  described  below:  shell 
plating,  plating  of  decks,  bulkheads,  inner  bottom,  etc., 
frames  and  reverse  frames,  floors,  keels  and  keelsons,  etc., 
deck  beams,  bulkhead  stiffeners,  brackets,  bounding  bars, 
coamings,  etc. 


186  PRACTICAL  SHIP  PRODUCTION 

Shell  Plating. — The  flat  plates  of  the  shell  present  little  or 
no  difficulty.  After  being  rolled  perfectly  flat,  or  mangled, 
if  necessary,  these  plates  are  laid  off  from  templates  similar 
to  that  shown  in  Fig.  77.  The  centres  of  the  rivet  holes 
are  centre  punched  on  the  side  of  the  plate  from  which  to 
be  punched  and  a  small  white  circle  is  marked  with  paint  or 
chalk,  to  make  the  position  of  each  more  conspicuous.  In 
some  cases  especial  pains  are  taken  to  have  these  small 
circles  exactly  concentric  with  the  centre  punch  marks  but 
this  is  not  absolutely  necessary,  provided  the  centre  punch 
mark  is  correctly  located  in  each  case.  If  holes  are  bored  in 
the  template,  as  shown  in  Fig.  77,  a  special  tool  is  used 
which  consists  of  a  short  hollow  cylinder  of  just  the  proper 
outside  diameter  to  fit  the  holes  in  the  template,  carrying 
a  spiral  spring  and  the  punch  inside,  properly  centred. 
By  dipping  this  tool  in  white  paint  both  the  centre  punch 
mark  and  the  white  circle  are  applied  to  the  plate  in  one 
operation.  Sometimes  simply  the  centre  of  each  rivet 
hole  is  indicated  on  the  template  and  a  small  centre  punch 
is  driven  right  through  the  soft  wood  of  the  template 
against  the  plate  over  which  it  is  clamped. 

The  diameters  of  the  holes  to  be  punched  are  indicated 
by  figures  painted  on  the  plate,  and  also  such  holes  as  are 
to  be  countersunk  are  suitably  marked.  The  symbol 
"CKOS"  denotes  " countersink  on  the  other  side." 
Edges  to  be  sheared  are  marked  on  the  plate  by  chalk 
or  soapstone  lines  and  are  also  reinforced  by  centre  punch 
marks  at  intervals.  The  symbol  "  •*&- ,"  is  often  employed 
to  indicate  lines  to  be  sheared.  In  addition  to  the  above, 
information  is  also  centre  punched  or  painted  on  the  plate 
regarding  any  other  operations  to  be  performed  such  as 
cutting  or  punching  of  large  holes,  or  notches,  planing, 
chamfering,  joggling,  etc.,  and  the  strake,  side  of  the  ship, 
and  serial  number  of  the  plate.  If  the  rivet  holes  are  to  be 
punched  small  for  subsequent  reaming  care  must  be  taken 
that  the  correct  sizes  of  the  punches  to  be  used  are  indicated. 
After  the  plate  has  been  laid  off  it  is  sent  to  the  plate  and 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION     187 

angle  shed  where  the  necessary  shearing,  punching,  planing, 
etc.,  is  done  as  described  in  the  preceding  chapter. 

When  this  has  been  done  the  faying  surfaces,  or  portions 
of  the  plate  that  will  rest  against  the  frames,  adjacent 
plates  or  other  members  are  carefully  cleaned  and  given 
a  coat  of  red  lead.  In  order  to  remove  mill  scale,  rust, 
etc.,  plates  and  shapes  should  be  pickled,  this  being  done, 
of  course,  before  the  faying  surfaces  are  red  leaded.  Pick- 
ling consists  in  placing  the  plate  or  shape  in  a  mixture 
of  acid  and  water  (usually  about  1  part  of  hydrochloric 
acid  to  19  parts  of  water)  which  eats  off  the  rust  and 
mill  scale.  The  plate  or  shape  is  then  removed,  well 
washed  and  brushed,  then  placed  in  an  alkaline  solution, 
then  removed,  finally  washed  with  water,  and  dried. 

The  rolled  plates  are  given  their  proper  curvature  in  the 
bending  rolls  as  described  in  Chapter  V.  The  shearing, 
punching,  planing,  countersinking,  etc.,  is  ordinarily  done 
before  the  plate  is  rolled,  but  the  template  must  be 
properly  made,  to  allow  for  the  change  in  distance  between 
rivet  holes,  caused  by  the  bending  of  the  plate.  Plates 
are  also  sometimes  given  a  " twist"  when  necessary,  by 
being  inserted  diagonally  in  the  bending  rolls. 

Furnaced  plates  present  the  greatest  difficulties.  A  bed  or 
frame  work  must  be  built  up  of  heavy  angles  and  plates 
to  the  proper  shape  so  that  the  plate  after  being  heated 
can  be  hammered,  in  this  bed,  to  the  correct  shape.  The 
rivet  holes  are  laid  off  and  punched  or  drilled  after  the 
f urnacing  is  completed.  The  edges  are  finished  by  chipping. 

Flanged  plates  may  or  may  not  have  the  punching  and 
countersinking  done  before  they  are  flanged.  They  are 
usually  sheared  and  planed,  however,  before  flanged. 

Plating  of  Decks,  Bulkheads,  Inner  Bottom,  Etc. — The 
plates  for  decks  and  bulkheads  are  practically  flat,  as  are 
the  most  of  those  for  the  inner  bottom.  The  raw  material 
is  marked  off  from  templates  in  much  the  same  manner 
as  the  flat  plates  of  the  shell.  The  fabrication  work 
consists  of  shearing,  planing,  punching,  countersinking, 
joggling,  cutting,  or  punching  of  manholes,  notches  or 


188  PRACTICAL  SHIP  PRODUCTION 

irregular-shaped  edges,  and,  in  the  case  of  margin  plates 
for  the  inner  bottom,  of  flanging.  The  templates  are 
usually  made  by  laying  down  the  part  in  question  to  full 
size  on  the  mold  loft  floor,  andjnaking  the  templates  from 
these  lines. 

The  manner  in  which  these  parts  are  fabricated  varies,  of 
course,  in  different  yards,  and  with  the  structural  design 
of  the  ship.  Bulkheads  are  usually  built  up  complete 
so  that  they  may  be  erected,  at  the  same  time  as  the  frames, 
with  their  bounding  bars  and  stiffeners.  Deck  plating 
is  often  fabricated  from  templates  " lifted"  or  made  from 
the  ship,  while  she  is  being  built,  after  the  deck  beams  are 
in  place.  Complete  detail  plans  of  each  bulkhead,  of 
each  deck,  and  of  the  inner  bottom  are  used  in  conjunction 
with  the  mold  loft  lines  in  making  the  templates. 

Frames  and  Reverse  Frames. — The  exact  shape  and 
size  of  the  heel  of  each  frame  is  shown  in  the  scrieve  board, 
which  is  really  a  full-sized  body  plan  of  the  ship.  A  mold 
is  made  of  the  transverse  flange  of  each  frame,  similar  to 
that  shown  in  Fig.  77.  In  addition  a  flexible  batten  is 
laid  on  the  scrieve  board  and  on  it  are  marked  off  the  land- 
ing edges  of  the  shell  plating,  edges  of  deck  plating, 
stringers,  etc.  At  the  same  time  a  bevel  board  is  made, 
this  being  a  small  strip  of  template  wood  on  which  are 
marked  pencil  lines  running  across  it  at  various  angles,  each 
being  properly  marked.  The  angles  that  these  lines  make 
with  the  side  of  the  bevel  board  are  the  angles  to  which 
the  frame  should  be  beveled  at  the  corresponding  points 
of  its  length. 

The  mold,  batten,  and  bevel  board  furnish  the  necessary 
data  from  which  the  frame  can  be  fabricated.  The  actual 
methods  of  fabrication  vary  considerably  depending  upon 
whether  the  frame  is  a  simple  angle  bar  or  a  channel, 
Z-bar,  or  bulb  angle,  whether  it  is  to  be  fitted  in  connection 
with  a  reverse  frame  or  not,  whether  it  has  excessive 
curvature  or  not,  and  upon  the  general  structural  design. 
It  is  difficult  to  punch  rivet  holes  in  a  frame  after  it  has 
been  bent,  but  on  the  other  hand  if  the  holes  are  punched  first 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION     189 


those  in  the  transverse  flange  are  liable  to  be  partially 
closed  during  the  bending  and  those  in  the  shell  flange 
stretched.  However,  the  difficulty  of  punching  holes 
in  the  transverse  flange  is  not  so  great  as  in  the  case  of  the 
shell  flange,  and  therefore,  as  a  general  rule,  the  holes 
in  the  transverse  flange  are  left  to  be  punched  after  the 

PLAN 


Pins 


Moon  Bar 


Bending : 

Slab 


SECTION  ON   B-B 


FIQ,  78. — Portion  of  bending'^slab,  showing  frame  bending/ 


frame  has  been  bent,  while  those  in  the  shell  flange  are 
punched  beforehand,  a  suitable  allowance  being  made  in 
laying  them  out  (based  upon  experience)  for  the  stretching 
of  this  flange  during  bending.  Where  the  curvature  is 
excessive  no  holes  are  punched  before  bending,  those  in  the 


190 


PRACTICAL  SHIP  PRODUCTION 


shell  flange  being  punched  later  in  a  horizontal  punch,  or 
drilled. 

The  method  of  bending  frames,  reverse  frames,  bulkhead 
boundary  bars  and  other  curved  shapes  is  shown  in  Fig. 
78.  The  shape  of  the  heel  of  the  bar  is  chalked  on  the 
bending  slab  and  another  line  is  laid  off  parallel  to  this  and 
inside  of  it  a  distance  equal  to  the  width  of  the  transverse 
flange.  A  soft  iron  bar,  called  a  set  iron  is  then  bent  to 
this  shape  and  clamped  in  place  by  means  of  pins,  wedges 
and  dogs  that  fit  into  the  holes  of  the  slabs,  as  shown  in 
the  figure.  The  frame  bar  having  been  heated  red  hot 


/Beveling1  Lever 


/Bending  Slab 


Bevel 
Tester 


Bevel 
Board 


FIG.  79. — Frame  beveling. 

in  the  reverberatory  furnace  is  dragged  out  onto  the  slabs 
and  one  end  is  placed  against  the  corresponding  end  of 
the  set  iron  with  the  toe  of  the  transverse  flange  against 
it,  as  shown  in  the  lower  right-hand  sketch  of  Fig.  78. 
This  end  is  then  secured  by  dogs  in  the  same  manner  as  the 
set  iron  and  the  frame  bar  is  bent  around  by  means  of 
moon  bars,  or  other  suitable  tools,  so  that  the  toe  of  the 
transverse  flange  finally  fits  against  the  set  iron  at  all 
points.  As  fast  as  each  few  inches  of  the  bar  have  been 
properly  bent  they  are  promptly  dogged  down  against 
the  slabs.  (These  dogs  are  not  shown  in  Fig.  78  but  one 
is  shown  in  Fig.  79.) 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION     191 

After  the  frame  has  been  completely  bent  to  shape,  the 
proper  bevels  are  given  to  it  at  all  points  of  its  length  by 
means  of  the  bevel  board  from  which  the  successive  bevels 
are  lifted  by  means  of  a  bevel  tester  or  adjustable  square, 
as  shown  in  Fig.  79.  The  opening  of  the  flange  is  accom- 
plished by  means  of  beveling  bars,  or  levers  of  which  one 
is  shown  in  the  sketch. 

Floors. — Templates  for  the  floor  plates  are  made  from 
the  scrieve  board.  In  the  case  of  ships  fitted  with  double 
bottoms  (which  is  generally  the  case  for  all  but  very  small 
ships)  the  floors  together  with  their  upper  and  lower  angles, 
connecting  clips,  etc.,  are  made  up  complete  so  that  they 
may  be  erected  and  bolted  to  the  vertical  keel  as  soon  as  the 
latter  is  in  place.  Horizontal  reference  marks  are  made  on 
the  templates  of  floor,  vertical  keel  angle,  margin  plate 
angle,  and  angles  for  longitudinals  so  that  the  rivet  holes 
will  come  correct.  These  same  templates  are  used  for  trans- 
ferring the  corresponding  rivet  holes  to  the  templates  for 
the  members  to  which  these  angles  are  to  be  secured.  Simi- 
lar vertical  guide  lines  are  marked  on  the  templates  of 
floor  and  frame  and  reverse  frame  angles. 

The  fabrication  of  the  floor  plates  consists  in  shearing, 
punching  and  cutting  of  lightening  holes,  drain  holes,  air- 
holes, limber  holes,  etc. 

Keel  Plates,  Longitudinals,  Etc. — The  plates  for  the  keel 
and  centre  vertical  keel  are  laid  off  from  templates  made 
from  the  mold  loft  lines,  and  plans  showing  the  details  of 
riveting,  butts,  etc.  These  templates  must  be  made  in 
conjunction  with  those  for  the  floor  connecting  angles  and 
frames  and  the  templates  for  top  and  bottom  angles  for 
the  vertical  keel  must  be  made  to  agree  with  those  for 
the  vertical  keel.  The  plates  for  the  vertical  keel  are  prac- 
tically all  flat  and  rectangular,  so  that  the  fabrication 
consists  in  shearing,  punching  and  cutting  of  lightening 
or  other  holes.  The  flat  keel  plates  are  slightly  dished  as 
a  rule,  this  being  done  after  they  have  been  punched. 
Those  at  the  ends,  which  connect  with  the  stem  and  stern 
frame,  are  considerably  dished  and  usually  have  to  be 


192  PRACTICAL  SHIP  PRODUCTION 

furnaced.  In  this  case  the  holes  may  be  drilled  after  the 
plates  have  been  shaped.  As  the  keel  is  the  first  part  of 
any  ship  to  be  erected  it  must  always  be  made  from  mold 
loft  templates  since  at  that  stage  there  are  no  other  parts 
in  place  from  which  to  "lift"  it. 

Longitudinals,  where  continuous,  as  in  warships,  are 
fabricated  in  much  the  same  way  as  centre  vertical  keel 
plates  from  mold  loft  templates.  In  merchant  ships, 
where  they  are  ordinarily  intercostal  the  longitudinals  are 
made  up  of  a  great  many  short  rectangular  plates.  Some- 
times these  are  flanged  at  each  end  for  connection  to  the 
floor,  in  order  to  avoid  the  use  of  clips. 

Longitudinal  members  outside  of  the  inner  bottom, 
such  as  bilge  and  hold  stringers  can  best  be  fabricated  from 
templates  lifted  after  the  frames  are  in  place,  though  these 
are  sometimes  made  in  advance. 

The  fabrication  work  consists  of  shearing,  punching,  and 
cutting  of  holes. 

Deck  beams  are  fabricated  in  advance,  at  the  same  time 
as  the  frames.  For  this  purpose  a  beam  mold  is  made,  this 
being  usually  of  wood  about  1"  thick,  with  one  edge  trimmed 
to  the  proper  camber,  and  of  length  sufficient  for  the  longest 
beams.  The  beams  are  bent  cold  as  a  rule  in  the  beam 
bending  machine  which  supports  a  portion  of  the  beam  at 
two  points  on  one  edge  while  the  other  edge  is  subjected 
to  pressure  midway  between  these  two  points  of  support. 
Templates  made  for  the  brackets  which  connect  the  beam 
ends  to  the  frame  bars  must  be  made  in  conjunction  with 
the  templates  for  the  frames. 

Bulkhead  stiff eners  are  ordinarily  laid  off  along  with  the 
bulkhead  plating  and  bounding  bars,  so  that  all  bulkheads 
may  be  assembled  and  riveted  up  as  units  which  can  be 
erected  complete. 

Brackets. — In  full-lined,  parallel  sided  ships  a  large  num- 
ber of  the  brackets  are  identical  and  can  be  laid  off  from  the 
same  template.  Sometimes  brackets  are  not  fabricated  in 
advance  but  are  lifted  from  the  ship. 

Bounding -bars  are  handled  in  much  the  same  way  as 


PRELIMINARY  STEPS  IN  SHIP  CONSTRUCTION     193 

frames,  being  laid  off  and  bent  and  beveled  on  the  bending 
slabs  in  a  similar  manner. 

The  exact  methods  of  fabricating  the  various  parts  of 
the  hull  vary  so  much  in  accordance  with  yard  practice 
and  the  structural  design  of  the  particular  ship  under  con- 
struction, that  little  is  to  be  gained  by  a  detailed  description 
of  the  work  in  any  one  case.  It  is  well  to  note,  however, 
certain  general  points  that  apply  to  all  ship  construction. 

The  templates  for  any  two  or  more  members  that  are  to 
be  fastened  together  must  be  made  in  conjunction  with 
each  other  so  that  rivet  holes  in  the  different  parts  will  be 
fair  when  they  are  erected  in  their  proper  positions  in  the 
ship. 

If  templates  are  to  be  made  in  advance  in  the  mold  loft 
the  chances  for  error  will  be  reduced  by  having  plans  pre- 
pared accurately  and  in  great  detail  to  show  all  measure- 
ments, locations  and  sizes  of  rivet  holes,  butt  straps,  liners, 
etc.  If  these  plans  are  made  with  sufficient  care  and  in 
enough  detail  practically  every  part  of  the  ship  can  be 
completely  fabricated  before  a  bit  is  erected.  (This 
accounts  for  the  rapidity  with  which  it  is  possible  to  build 
ships  after  the  keels  have  been  laid.) 

Whether  all  the  members  are  to  be  templated  in  advance 
of  the  commencement  of  building  on  the  ways  or  not,  the 
flat  and  vertical  keel  plates,  inner  bottom  framing,  margin 
plate  and  usually  some  of  the  bottom  shell  plating  must 
be  got  out  in  advance.  These  parts  must  be  carefully 
prepared  so  as  to  fit  fairly,  each  with  its  neighbor,  when 
erected. 

Where  rivet  holes  are  to  be  punched  only  and  not  reamed 
it  is  usually  necessary  to  punch  some  from  one  side  and  some 
from  the  other  of  certain  plates.  Hence  in  marking  them 
off  care  must  be  taken  to  mark  all  rivet  holes  on  the  correct 
side  or  the  faying  side  of  these  plates  so  that  they  may  be 
punched  from  that  side. 

Plates  and  shapes  should  be  pickled  to  remove  all  rust 
and  mill  scale.  After  fabrication  they  should  be  red  leaded 

13 


194  PRACTICAL  SHIP  PRODUCTION 

well  over  all  faying  surfaces,  and  identification  marks 
carefully  painted  on  them. 

For  the  best  class  of  work  rivet  holes  should  be  punched 
small  and  reamed  after  the  work  is  in  place.  This  not 
only  makes  possible  more  efficient  riveting  and  increases 
the  strength  by  cutting  away  the  material  around  the 
hole  that  is  weakened  by  punching  but  it  gives  more 
leeway  for  reaming  unfair  holes  and  thus  minimizes  the 
amount  of  drifting  that  must  be  resorted  to. 

All  fabrication  work  should  be  carefully  done,  and  tem- 
plates followed  exactly.  Otherwise  the  parts  will  not  fit 
properly  in  place  when  erected  and  filling  in  pieces,  extra 
liners,  and  excessive  reaming,  will  be  necessary  and 
imperfect  calking,  and  consequent  loss  in  strength  and 
water-tightness  will  be  caused. 


CHAPTER  VII 
THE    BUILDING     OF     SHIPS 

1.  ERECTION 

The  first  step  in  the  actual  building  of  a  ship  is  the  laying 
of  the  keel,  and  this  being  one  of  the  principal  events  in  the 
process  of  ship  production,  is  often  the  occasion  of  an 
accompanying  ceremony.  The  time  required  to  build  a 
ship  is  frequently  measured  from  the  date  that  the  keel  is 
laid  to  the  date  when  the  hull  is  launched.  This  how- 
ever does  not  give  a  true  idea  of  the  time  required  to  pro- 
duce the  ship,  unless  the  length  of  time  spent  in  fabrication 
work  previous  to  the  laying  of  the  keel,  and  the  length  of 
time  necessary  to  complete  the  vessel  after  she  is  launched 
are  also  known. 

The  amount  of  preliminary  work  actually  necessary  for 
the  laying  of  the  keel  is  slight,  since  all  that  is  done  in  the 
actual  operation  is  to  set  in  position  two  or  three  of  the  flat 
keel  plates — or  a  few  sections  of  the  bar  keel  (if  that  is  the 
type  keel  used).  After  this  has  been  done  however  the 
work  of  erection  cannot  proceed  rapidly  unless  a  large 
amount  of  fabricated  material  is  on  hand,  and  therefore  it 
is  ordinarily  the  practice  to  delay  the  laying  of  the  keel 
until  the  getting  out  of  the  fabricated  material  has  been 
under  way  for  several  weeks,  or  perhaps  months. 

The  keel  blocks  have  been  described  in  Chapter  V.  In 
order  to  prepare  them  for  the  keel-laying  the  upper  surface 
of  the  highest  of  each  group  of  blocks  must  be  carefully 
trimmed  off  so  that  all  are  in  a  straight  line  having  the 
proper  slope  (which,  as  previously  stated,  commonly 
ranges  between  % 6"  and  iJKe"  per  foot)  and  have  their 
surfaces  square  to  the  central  longitudinal  plane  of  the 
ship.  The  appearance  of  a  set  such  blocks,  ready  for 

195 


196  PRACTICAL  SHIP  PRODUCTION 

the  laying  of  the  keel  is  shown  in  the  foreground  of  the 
picture,  Fig.  69.  A  straight  line  is  drawn  across  the  top 
of  each  upper  block  to  indicate  the  exact  centre  line  of 
the  ship. 

After  the  first  few  keel  plates  have  been  carefully  lowered 
into  position  on  top  of  the  blocks  (by  means  of  derricks  or 
cranes),  so  that  their  centre  line  coincides  exactly  with 
the  line  drawn  on  the  blocks,  and  they  have  been  correctly 
located  in  a  fore  and  aft  direction,  the  connecting  butt 
straps  are  bolted  in  place  and  the  other  plates  of  the  flat 
keel  are  lowered  into  place  one  at  a  time,  carefully  set, 


FIG.  80. — Flat  and  centre  vertical  keel  plates  in  place  on  blocks. 

and  similarly  secured  to  their  neighbors  by  their  butt  straps. 
On  top  of  the  flat  keel  plates  are  then  placed  the  plates 
of  the  vertical  keel,  with  its  two  lower  connecting  angles, 
which  are  bolted  in  place.  In  Fig.  80  is  shown  a  picture  of 
some  of  the  flat  and  vertical  keel  plates  with  their  connect- 
ing angles  in  place  on  the  keel  blocks.  It  will  be  noted  that 
only  a  few  bolts  are  necessary  to  hold  them  in  place,  these 
being  inserted  through  rivet  holes.  The  rivet  holes  for 
the  connecting  angles  by  means  of  which  the  floor  plates 
will  be  attached  to  the  centre  vertical  keel,  and  also  those 


THE  BUILDING  OF  SHIPS 


197 


for  the  top  angles  of  the  vertical  keel  are  plainly  seen  in 
the  picture.  The  flat  plate  keel  butts  in  this  case  are  lapped 
instead  of  butted. 

In  order  to  bring  the  rivet  holes  in  connecting  members 
into  alignment  a  drift  pin  is  driven  into  some  convenient 
rivet  hole  so  that  its  wedge-like  action  will  cause  the  two 
members  to  slide  along  the  faying  surface,  as  shown  in  Fig. 
81,  until  the  rivet  holes  come  fair.  If  all  of  the  holes  are 
not  correctly  punched  in  bringing  one  hole  fair  one  or  more 


FIG.  81. — Drifting. 

other  holes  may  be  made  unfair.  If  the  unfairness  is  too 
great  the  replacement  of  one  of  the  members  may  be  nec- 
essary— with  consequent  waste  of  material  and  loss  of 
time  and  labor. 

It  is  usually  customary  in  the  case  of  merchant  ships, 
which  have  comparatively  flat  bottoms,  to  erect  the  bottom 
plating  soon  after  the  flat  and  vertical  keel  plates  are  in 
place.  In  order  to  support  these  bottom  strakes  during 
this  process  heavy  wooden  athwartship  timbers  are  used 
placed  at  intervals  along  the  ship's  length  normal  to  the 
keel  line,  as  shown  in  Figs.  82  and  83.  The  bottom  plating 
out  to  and  including  the  first  curved  bilge  strake  is  usually 
so  handled — as  shown  in  the  pictures. 

On  top  of  the  bottom  shell  plating  is  next  placed  the 
double  bottom  framing,  which  consists  of  frames,  reverse 


198 


PRACTICAL  SHIP  PRODUCTION 


frames,  and  floor  plates  with  their  connecting  clips.  In 
the  case  of  the  ship  shown  in  Fig.  82  bracket  floors  are  used, 
one  of  which  is  shown  being  lowered  into  place  by  the  crane. 


FIG.  82. — Erecting  double  bottom  framing. 

This  picture  gives  a  view  looking  aft  along  the  centre  line 
of  the  ship  over  the  top  of  the  centre  vertical  keel,  which, 
not  yet  having  been  completely  secured,  presents  a 


FIG.  83. — Portion  of  double  bottom  framing  completely  erected. 

"wobbly"  appearance.     A  portion  of  the  port  top  vertical 
keel  angle  is  shown  in  place. 

A  view  showing  the  erection  somewhat  further  advanced 
is  given  in  the  picture  in  Fig.  83.     Here  a  complete  portion 


THE  BUILDING  OF  SHIPS 


199 


200  PRACTICAL  SHIP  PRODUCTION 

of  the  double  bottom  framing  is  erected  and  the  clips  for 
the  margin  plate  and  the  supports  for  the  tank  top  plating 
can  be  seen.  In  the  lower  right-hand  portion  of  the  picture 
will  be  seen  some  of  the  connecting  clips  by  means  of  which 
floors  are  to  be  attached  to  the  centre  vertical  keel.  The 
angle  at  which  the  top  line  of  the  keel  blocks  is  set  with 
the  horizontal  is  also  clearly  visible. 

The  next  step  is  the  erection  and  bolting  up  of  tank  top 
plating,  margin  plates  and  the  brackets  for  the  attachment 
of  frames.  Figure  84  is  a  picture  showing  the  bottom  por- 
tion of  a  ship  under  construction,  of  which  all  the  inner  bot- 
tom framing  has  been  completed,  and  a  portion  of  the  tank 
top  plating,  margin  brackets,  shaft  alley  framing  and  plat- 
ing, and  after  portion  of  engine  room  have  been  erected. 
Several  frames  on  the  starboard  side,  one  on  the  port 
side,  one  deck  beam  and  two  plates  of  a  bulkhead  just  a 
little  aft  of  these  have  also  been  erected.  When  the 
construction  has  advanced  this  far  a  certain  amount  of  the 
riveting  in  the  double  bottom  should  also  have  been  accom- 
plished, since  it  is  much  easier  for  the  riveters  to  do  their 
work  in  these  spaces  before  the  tank  top  plating  is  in 
place. 

As  the  hull  is  gradually  built  up  shores  are  placed  under 
the  bottom  to  support  the  increasing  weight  of  the  material 
in  place.  Some  of  these  will  be  noted  in  Fig.  84,  and  also 
the  lower  portions  of  the  scaffolding  on  each  side  of  the 
ship,  which  will  soon  have  to  be  built  up  higher  for  use  of 
the  workmen  in  erecting  the  frames,  beams,  bulkheads,  etc. 

The  erection  of  the  side  frames  is  next  proceeded  with, 
together  with  deck  beams,  bulkheads,  stanchions,  girders, 
stringers,  engine  and  boiler  foundations,  shaft  alleys,  etc. 
Fig.  85  shows  a  ship  under  construction  with  a  number  of 
side  frames  and  lower  deck  beams,  stanchions,  etc.,  in  place. 
The  coaming  for  the  after  cargo  hatch  in  the  lower  deck 
can  be  seen,  and  also  the  shaft  tunnel,  shoring  under  bottom, 
derricks  and  scaffolding  used  in  erecting  and  bolting  up 
the  various  members,  deck  beam  brackets,  etc. 

In  order  to  hold  the  side  frames  in  their  correct  positions, 


THE  BUILDING  OF  SHIPS 


201 


202 


PRACTICAL  SHIP  PRODUCTION 


after  they  have  been  carefully  set  at  the  proper  rake  with 
the  vertical  (to  allow  for  the  slope  of  the  keel  blocks) 
by  means  of  a  plumb-bob  and  ''declivity  board,"  and  square 
to  the  keel  line,  longitudinal  wooden  pieces  called  ribbands 
are  temporarily  installed  along  the  shell  flanges.  These 
are  heavy  timbers,  which  are  fitted  along  the  frames  in 


Lightening  Hole 
Margin  Plate  Bracket 


FIG.  86. — Cross  section  of  building  slip. 


way  of  outer  strakes,  being  clamped  to  each  frame  by  means 
of  a  bolt  and  small  plate  washer.  As  they  have  only  a 
slight  "give"  they  serve  to  fair  the  frames  and  as  they  run 
along  the  spaces  to  be  subsequently  occupied  by  outer 
strakes  they  do  not  interfere  with  the  bolting  up  of  the 
plates  of  the  inner  strakes.  After  the  inner  strakes,  and 
deck  stringer  plates,  hold  stringers,  etc.,  have  been  bolted 


THE  BUILDING  OF  SHIPS 


203 


up,  the  ribbands  are  removed  and  the  outer  strakes  put  in 
place  and  bolted  up.  At  the  ends  of  the  ship,  where 
the  curvature  is  sharp,  special  timbers  have  to  be  used, 
carefully  cut  to  shape  from  the  mold-loft  lines,  to  per- 
form the  same  functions  in  these  places  that  the  ribbands 
perform  in  the  middle  body.  These  timbers  are  called 
harpins. 

The  building  slips  shown  in  Figs.  84  and  85  are  heavy  plat- 
forms built  over  the  tops  of  the  piling  (see  also  Fig.  69). 
More  often  it  is  the  practice  to  lay  the  keel  blocks  on  cross 
logs  at  the  ground  level  (see  Fig.  86). 


FIG.  87. — Wooden  ship  under  construction. 

After  the  side  frames  have  been  erected  the  side  shell 
plating  is  put  in  place  and  bolted  up,  and  the  erection  of 
deck  beams,  deck  stringer  plates,  deck  plating,  coamings, 
bulkheads,  stanchions,  and  in  fact  all  of  the  various  interior 
members  is  proceeded  with,  certain  riveting  and  calking 
of  the  portions  of  the  hull  that  are  now  completely  erected 
being  taken  up  concurrently. 

The  remainder  of  the  erection  work  is  of  a  miscellaneous 
character  and  goes  on  while  the  riveting  and  calking  of 
the  lower  portion  is  being  done  right  up  to  and  even  after 


204  PRACTICAL  SHIP  PRODUCTION 

the  launching.  As  the  hull  rises  the  scaffolding  on  each 
side  is  extended  up  (see  Figs.  85  and  86)  and  stage  planks 
are  placed  on  it  for  use  of  the  bolters  up,  riveters  and 
calkers. 

The  order  in  which  the  parts  are  erected  in  a  wooden 
ship  is  practically  the  same  as  for  a  steel  ship.  Figure  87 
shows  such  a  ship  under  construction.  (Note  the  double 
frames.) 

2.  BOLTING  UP,  DRILLING  AND  REAMING 

As  soon  as  any  part  of  a  ship  has  been  placed  in  its 
proper  position  it  is  bolted  up,  or  secured  temporarily,  by 
bolts  placed  at  intervals  through  the  rivet  holes,  to  the  ad- 
jacent parts  to  which  it  is  finally  to  be  riveted.  At  this  stage 
of  the  construction  unsatisfactory  workmanship  in  the  fab- 
rication, if  such  exists,  will  be  made  evident.  There  are 
two  conditions  that  must  be  strictly  fulfilled,  if  the  con- 
struction is  to  be  satisfactory,  in  the  case  of  each  and  every 
structural  member  of  the  hull: 

1.  Each  must  be  in  the  correct  position  as  called  for  by 
the  plans,  and 

2.  Each  must  have  all  of  its  rivet  holes  come  fair  with 
those  of  the  adjacent  members. 

When  all  the  parts  have  been  properly  shaped  and  the 
rivet  holes  have  all  been  correctly  laid  out  and  punched 
both  of  these  conditions  can  be  fully  met.  In  practice, 
however,  unless  extreme  care  is  used  and  all  the  workmen 
are  highly  skilled,  this  will  seldom  be  the  case.  In  bringing 
one  part  into  its  proper  position  it  will  often  be  found  that 
the  rivet  holes  for  connecting  it  to  its  neighbor  will  be  drawn 
out  of  alignment,  or  conversely  in  attempting  to  bring 
into  alignment  the  rivet  holes  of  a  part  already  in  its 
correct  place,  that  part  may  be  forced  out  of  its  proper 
position. 

During  the  bolting  up  all  such  defects  should  be  noted 
so  that  they  may  be  remedied  before  the  riveting  is  started. 
All  parts  should  be  true  and  fair  and  free  from  dents,  hol- 
lows, unevennesses  or  other  imperfections  that  would 


THE  BUILDING  OF  SHIPS  205 

prevent  satisfactory  riveting  and  calking  (which  will  be 
described  below). 

Members  that  are  not  to  be  riveted  until  a  fairly  late 
stage  of  the  construction,  or  for  which  the  adjoining  parts 
are  to  be  temporarily  omitted  for  purposes  of  access,  etc., 
must  be  especially  well  bolted  up  and  secured  by  temporary 
wooden  tie  pieces,  shores,  etc.,  in  order  to  prevent  their 
shifting  out  of  place. 

All  sharp  and  jagged  edges,  burrs,  etc.,  should  be  removed. 

In  certain  places,  where  oil-,  or  water-tightness  is  re- 
quired, oil  stops  or  stopwaters  must  be  fitted  between  the 
adjoining  steel  members.  These  consist  of  canvas,  hair 
felt,  lamp  wick,  etc.,  treated  with  various  paints,  etc.,  and 
will  be  described  more  in  detail  later.  These  must  be 
fitted,  however,  during  the  process  of  bolting  up. 

Reaming. — After  the  members  have  been  properly 
aligned,  fitted  and  bolted  up  the  rivet  holes  must  be  reamed. 
This  is  necessary  to  remove  the  slight  unfairnesses  that  are 
almost  inevitable  on  account  of  the  inaccuracies  of  laying 
out  and  punching  the  rivet  holes,  and  is  also  often  done  to 
enlarge  the  holes,  which  are  punched  small  for  this  purpose, 
so  as  to  make  a  neat  fit  for  the  rivets  and  to  remove  the  por- 
tion of  metal  just  outside  of  the  hole,  which  is  weakened 
by  the  action  of  the  punch.  In  addition,  in  certain  cases, 
reaming  is  necessary  to  remove  the  taper  that  the  holes 
have  as  a  result  of  punching  (see  middle  sketch  of  Fig.  89) . 

In  Fig.  88  is  shown  a  sketch  of  a  reaming  tool  or  reamer 
which  fits  in  a  machine  run  by  compressed  air.  The 
end  is  tapered  so  that  the  reamer  can  be  inserted  into 
rivet  holes  that  are  unfair.  (See  third  hole  from  left 
in  bottom  sketch  of  Fig.  88).  In  reaming  holes  it  is 
important  that  the  finished  hole  should  be  normal  to  the 
plate  and  also  that  it  is  not  of  too  great  a  diameter.  In 
Fig.  88  are  shown  various  types  of  rivet  holes.  The  one 
to  the  left  is  perfectly  fair  and  will  require  little  or  no 
reaming.  The  next  is  only  slightly  unfair  and  can  be 
reamed  with  only  a  small  increase  in  diameter.  The  next 
can  be  reamed  but  the  diameter  of  the  resulting  hole  will 


206 


PRACTICAL  SHIP  PRODUCTION 


be  considerably  greater  than  would  have  been  necessary 
had  the  parts  been  properly  fitted.  The  right-hand  hole, 
which  is  half  blind,  is  so  unfair  that  it  should  not  be  reamed 
since  the  resulting  hole  would  be  altogether  too  large. 

Where  holes  come  unfair  there  is  a  temptation  to  avoid 
increasing  the  diameter  by  running  the  reamer  through  at 
an  angle.  If  the  angle  is  very  slight,  this,  though  poor 
workmanship,  is  sometimes  permissible,  but  if  too  great 
will  cause  a  weakening  of  the  joint  preventing  the  rivet 


Shank' 


utes 


REAMER 
( Taper  about  %'per  foot) 


Perfectly 
Fair 


Nearly 
Fair 


Can  be 
Reamed 


Too  Unfair 
for  Reaming 


RIVET  HOLES 
FIG.  88. — Reaming. 

from  filling  the  hole  completely.  Examples  of  the  results 
of  improper  fitting  and  reaming,  and  of  failure  to  ream 
at  all  in  the  case  of  "  three-ply "  riveting  are  shown  in  Fig. 
89.  When  the  driven  rivet  is  not  of  the  designed  diameter, 
or  does  not  fill  the  hole  completely  it  loses  in  efficiency, 
and  the  strength  of  the  whole  joint  is  consequently  reduced. 
If  many  unfair  holes  occur  this  will  be  a  serious  matter 
and  may  endanger  the  ship. 


THE  BUILDING  OF  SHIPS 


207 


It  is  also  important  to  see  that  the  burrs  on  the  edges 
of  rivet  holes  or  shavings,  etc.,  do  not  prevent  the  faying 
surfaces  from  being  drawn  tightly  together  when  riveted. 

Drilling. — It  is  not  practicable  to  have  all  rivet  and  other 
holes  punched  in  advance,  and  it  is  therefore  necessary  to 
have  certain  drilling  (and  countersinking)  done  after  the 
material  is  in  place  in  the  ship.  Such  holes  are  those  in 
castings,  forgings  and  furnaced  parts  that  cannot  be 
conveniently  punched,  holes  the  exact  locations  of  which 


Holes  reamed  at  an  angle 


Punched  holes,  in  three-ply  riveting,  not  reamed. 


Unfair  hole 
in  centre  ply. 


Hole  reamed 
at  an  angle. 


FIG.  89. — Effect  of  unfair  rivet  holes  and  improper  reaming. 

are  not  known  in  advance  (such  as  those  for  voice  tubes,  pip- 
ing systems,  electric  conduits,  etc.)  and  certain  rivet  holes 
for  work  that  requires  extreme  accuracy,  as  in  the  case  of 
oil- tight  work,  work  on  submarines,  etc. 

Drilling  may  be  done  by  means  of  electric  or  pneumatic 
tools,  or  by  the  ordinary  hand  ratchet  drill.  The  former 
are  much  more  rapid  processes  than  the  latter,  but  all 
are  very  slow  compared  to  the  punching  and  reaming 


208 


PRACTICAL  SHIP  PRODUCTION 


method.  On  the  other  hand,  absolute  accuracy  and 
practically  perfect  riveting  can  thus  be  attained  and  the 
material  is  not  weakened  thereby,  as  when  punched. 

The  method  of  using  the  pneumatic  drilling  machine 
is  shown  in  the  sketch  in  Fig.  90.  The  upper  end  of  the 
apparatus  is  pressed  down  by  some  sort  of  a  rig  similar 
to  that  shown  in  cases  where  some  rigid  bearing  for  the 
upper  end  of  the  machine  is  not  at  hand.  When  a  portion 
of  the  ship  may  be  used  as  a  bearing  the  drill  is  gradually 
advancd  by  screwing  up  the  top  spindle  by  means  of  the 
upper  handle  shown  in  the  sketch.  When  a  wooden  stick 


Pressure 


Tie  Rod 


Handle 


_J2 


Combined  Handle  and 

Compressed  Air  Pipe 

and  Valve 


Nut' 
FIG.  90. — Method  of  using  pneumatic  drilling  machine. 

is  used,  as  shown,  this  is  accomplished  without  the  use 
of  this  handle  by  simply  keeping  pressure  on  the  end  of 
the  stick.  The  two  handles  on  each  side  of  the  machine 
are  grasped  by  the  operator  in  guiding  and  running  it, 
one  of  them  serving  also  as  a  means  for  starting  and  stop- 
ping the  machine.  This  machine  can  also  be  used  for 
reaming  and  countersinking  by  replacing  the  drill  by  a 
reamer  or  countersink.  With  the  ordinary  hand  ratchet 
drill  a  portable  arm  or  support,  called  an  "old  man" 
is  used. 

The  speed  with  which  drilling  can  be  accomplished  de- 
pends upon  the  diameter  of  the  holes,  the  thickness  and 
nature  of  the  material  to  be  drilled,  the  accessibility, 


THE  BUILDING  OF  SHIPS  209 

condition  of  tools,  air  pressure,  etc.  Similarly  with  ream- 
ing and  countersinking,  though  the  latter  of  course  should 
require  much  less  time,  per  hole,  than  drilling.  It  is 
not  at  all  difficult,  under  good  conditions,  for  a  workman 
to  ream  and  countersink  800  or  900  holes  in  a  day. 

Drillers  are  also  required  to  drill  and  tap  holes  for  bolts 
and  screws  (see  Section  3,  below). 

Great  care  should  be  exercised  and  efficient  supervision 
maintained  to  see  that  holes  are  drilled  and  reamed  properly, 
otherwise  defective  riveting  is  bound  to  result.  It  is 
important  that  all  holes  should  be  perfectly  cylindrical, 
normal  to  the  faying  surfaces,  of  the  proper  diameter, 
and  that  burrs,  borings,  pieces  of  metal,  or  other  foreign 
materials  do  not  get  between  the  faying  surfaces. 

3.  RIVETING 

As  has  already  been  noted  riveting  is  of  the  greatest 
importance  in  shipbuilding.  All  the  structural  members 
of  a  steel  ship  (except  in  the  case  of  welded  ships  which  are 
described  below)  are  tied  together  by  riveting  so  as  to 
act  as  a  complete  unit.  If  the  rivets  are  not  absolutely 
tight,  of  the  designed  size  and  strength,  and  located  as 
provided  for  in  the  design,  the  strength  of  the  ship  is  bound 
to  be  impaired.  While  a  factor  of  safety  is,  of  course, 
used  in  designing  such  a  ship,  nevertheless  a  certain  amount 
of  careless  workmanship  may  have  serious  results.  It 
will  be  readily  seen  that  some  of  the  rivets  in  Fig.  89 
can  come  nowhere  near  performing  the  functions  for  which 
they  were  designed.  For  example,  the  upper  right-hand 
rivet,  being  reduced  in  sectional  area  at  the  faying  surface, 
has  its  shearing  strength  reduced,  while  in  the  case  of 
bearing  pressure  it  can  develop  practically  no  strength. 

It  is,  of  course,  evident  that  in  many  cases  defective 
riveting  is  not  directly  the  fault  of  the  riveting  gang,  but 
rather  of  the  layers-out,  or  the  punch  operators,  or  the 
drillers  or  reamers.  Nevertheless  a  certain  responsi- 
bility must  rest  with  the  riveters,  for  rivets  should  never 
be  driven  in  holes  that  have  not  first  been  properly  prepared. 


14 


210 


PRACTICAL  SHIP  PRODUCTION 


The  operation  of  driving  a  rivet  is  shown  in  the  sketch 
in  Fig.  91.  Having  removed  the  bolt,  if  any,  from  the  rivet 
hole  the  holder-on  inserts  the  hot  rivet  in  the  hole  and  drives 
it  well  home  so  that  the  head  rests  tightly  against  the  inner 
plate,  around  the  inner  end  of  the  hole,  with  the  holding-on 
hammer,  a  large,  heavy  headed  hammer,  which  he  then 
presses  hard  against  the  rivet  head.  The  riveter,  on  the 
other  side  of  the  plates  then  proceeds  to. stave  in  or  drive 


Holding-on 
Hammer    \ 


ot  Rivet 


Riveting 
Hammer 


FIG.  91. — Driving  a  rivet. 

the  rivet,  either  by  means  of  a  hand  or  a  pneumatic  riveting 
hammer,  so  as  completely  to  fill  the  hole.  In  order  to  be 
sure  that  the  rivet  has  sufficient  volume  for  this  purpose 
it  is  selected  a  trifle  long,  and  after  it  has  been  well  clinched, 
the  excess  metal  is  cut  off  with  a  chipping  tool  by  the  riv- 
eter and  the  point  smoothed  up  and  finished  after  it  has 
cooled  slightly.  In  order  to  permit  of  this  cooling  it  is 


THE  BUILDING  OF  SHIPS 


211 


usual  to  drive  one  more  rivet  and  then  go  back  to  finish 
off  the  rivet  driven  just  previously. 

Various  methods  of  holding-on  are  in  use.  Sometimes 
instead  of  a  hand  holding-on  hammer  a  pneumatic  one  may 
be  used,  this  consisting  of  a  cylinder  and  piston  secured  at 
the  end  of  a  stiff  brace  or  rod.  In  cramped  and  other  in- 
accessible places  a  curved  or  offset  holding-on  tool  is  used, 
commonly  known  as  a  "dolly  bar"  (see  Fig.  91). 


Countersunk 

head,  angle 

too  small . 


Hammered  point, 
too  low. 


Button 

point,  not 

symmetrical, 

plate  scored. 


Excessive  burr 

on  plates  not 

removed . 


Plates  not  drawn 

together.  Drillings 

between  plates. 


Hole  too  large,  not 

completely  filled 

by  rivet. 


FIG.   92. — Improperly  driven  rivets. 


When  properly  driven  the  head  and  point  of  a  rivet 
should  be  symmetrical  about  the  axis  of  the  rivet,  the  plates 
around  them  should  not  be  marred  or  scored  and  the  two 
plates  should  be  drawn  tightly  together.  The  shrinkage 
of  the  rivet  in  cooling,  especially  if  a  long  one,  has  a  tend- 
ency to  accomplish  this  result.  The  same  applies,  of  course, 
to  two  shapes,  or  a  plate  and  a  shape,  riveted  together. 

In  order  to  test  the  quality  of  riveting  the  heads  and 
points  should  be  inspected  visually,  and  tapped  with  a 
hammer — it  being  possible  to  tell  by  the  sound  and 
"feel"  whether  the  rivet  is  tight  or  loose.  With  a  thin 


212 


PRACTICAL  SHIP  PRODUCTION 


flat  knife  or  "  feeler "  it  is  possible  to  determine  whether 
or  not  the  faying  surfaces  have  been  properly  drawn 
together. 

In  Fig.  92  are  shown  a  few  examples  of  rivets  that  have 
not  been  properly  driven.  These  together  with  those 
shown  in  Fig.  89  represent  a  few  of  the  kinds  of  unsatis- 
factory workmanship  in  riveted  joints  that  may  be  met  with 
in  practice — all  of  which  should  be  avoided,  since  they  re- 
duce the  structural  strength  and  water-tightness  of  the 
ship.  It  will  be  noted  that  defects  in  riveted  work  may  be 
due  to  carelessness  or  lack  of  skill  of  any  or  all  of  the  follow- 
ing workmen :  loftsmen,  layers-out,  workers  in  the  fabricat- 
ing shops,  bolters-up,  drillers,  reamers  or  riveting  gangs. 


Effective 
Not  Effective 


UNSAFE  LOADING 


SAFE  LOADING 

FIG.  93. — Safe  and  unsafe  loading  of  ropes. 

Nevertheless  the  final  blame  attaches  to  any  riveter  who 
drives  a  rivet  in  a  hole  that  has  not  been  properly  prepared 
to  take  it,  or  who  does  not  do  his  own  work  properly. 

Defective  riveting  is  not  only  a  source  of  actual  danger 
to  a  ship,  but  is  the  direct  cause  of  added  cost  in  her  upkeep, 
since  if  the  riveting  is  not  properly  done  leaks,  straining  of 
the  hull,  and  excessive  corrosion  will  be  continually  occur- 
ring as  the  ship  is  subjected  to  the  various  strains  incident 
to  her  service.  Therefore  too  much  emphasis  cannot  be 
laid  on  the  importance  of  requiring  good  riveting. 

The  action  of  rivets  in  maintaining  strength  and  water- 
tightness  may  be  illustrated  by  comparison  with  the  case 
of  a  suspended  weight.  Suppose  that  a  piece  of  rope  is 


THE  BUILDING  OF  SHIPS 


213 


just  strong  enough  to  support  a  weight  of  one  ton.  If 
this  weight  be  suspended  by  the  rope,  as  shown  in  the 
left  sketch  of  Fig.  93,  the  strength  of  the  rope  will  be 
effective,  and  a  condition  of  safe  loading  will  exist. 

Three  pieces  of  this  same  rope  will  support  a  weight  of 
three  tons,  provided  that  the  strength  of  each  piece  is  effect- 
ive. In  the  right  sketch  of  Fig.  93  one  piece  of  rope  is 
longer  than  the  other  two,  and  consequently  its  strength 
is  not  effective.  The  other  two  pieces  can  support  only 
two  tons,  the  condition  of  loading  is  unsafe,  and  the  two 
outer  ropes  will  break  if  the  three-ton  weight  is  given  no 
support  other  than  that  of  the  ropes. 


SAFE 


FIG.  94. — Safe  and  unsafe  loading  of  riveted  joints. 

In  the  case  of  riveted  joints  a  similar  principle  applies. 
In  the  upper  sketch  of  Fig.  94  is  shown  a  safely  loaded 
riveted  joint  in  which  is  a  perfectly  driven  rivet,  large 
enough  to  withstand  a  pull  of  ten  tons.  In  the  lower  sketch 
is  shown  a  joint  with  three  of  the  same  sized  rivets,  but  one 
of  them  is  defective  so  that  it  furnishes  no  assistance  to 
the  other  two.  The  efficiency  of  this  joint  is  only  two-thirds 
of  what  it  should  be,  and  the  joint  would  fail  under  a  30- 
ton  pull. 

When  ships  are  designed  a  factor  of  safety  is  of  course 
assumed,  but  this  factor  of  safety  is  itself  based  on  an 
assumption,  since  there  is  no  way  of  determining  accurately 


214  PRACTICAL  SHIP  PRODUCTION 

the  stresses  to  which  a  ship  may  be  subjected  when  at  sea 
in  a  gale  or  hurricane.  Consequently  a  sufficient  number 
of  defective  rivets  might  cause  a  ship  to  be  lost  at  sea. 
Such  cases  have  actually  occurred. 

The  speed  of  production  of  steel  ships  is  necessarily 
dependent  upon  the  speed  with  which  the  riveting  is  ac- 
complished. Practically  all  the  structural  joints  of  such 
ships,  as  usually  built,  are  riveted,  and  a  moderate  sized 
ship  will  contain  over  a  million  rivets.  If  one  gang  of  riv- 
eters drives  400  rivets  per  day,  on  an  average,  it  will  thus  be 
seen  that,  to  accomplish  the  riveting  of  such  a  ship  in 
three  months,  over  27  gangs  of  riveters,  working  every  day 
of  the  week  would  be  required.  A  yard  building  ten  such 
ships  at  a  time,  at  this  rate,  would  require  nearly  300  gangs 
of  riveters — an  unusually  large  number. 

The  speed  with  which  rivets  can  be  driven  depends  upon 
the  size  of  the  rivets,  the  quality  of  the  reaming  and  coun- 
tersinking, the  manner  in  which  the  bol'ting-up  has  been 
done,  whether  the  holes  are  "scattered"  or  not,  the  accessi- 
bility of  the  work,  the  air  pressure,  the  condition  of  the 
tools,  the  prevailing  weather  conditions,  etc.  Under  fair 
average  conditions  it  may  be  said  that  it  might  easily  be 
possible  for  a  skilled  riveting  gang  to  average  50  rivets  per 
hour  or  400  in  an  eight-hour  day.  As  a  matter  of  fact 
single  riveting  gangs  have  actually  driven  several  thousand 
rivets  in  a  day,  per  gang,  but  this  must  be  considered  as 
unusual. 

A  close  supervision  over  all  riveting  should  be  main- 
tained during  the  construction  of  the  ship.  All  rivets  should 
be  carefully  tested  and  those  found  defective  marked. 
Some  may  be  made  good  by  rehammering,  but  others  will 
have  to  be  cut  out  and  new  rivets  driven  in  their  places. 
The  methods  of  cutting  out  rivets  are  illustrated  in  Fig. 
95.  Button  or  hammered  points  are  cut  away  by  the 
chippers  and  the  rivets  then  knocked  out  by  means  of  a 
backing-out  punch  and  hammer.  In  the  case  of  a  counter- 
sunk point  a  hole  of  nearly  the  size  of  the  rivet  is  drilled 
so  that  the  remaining  ring  of  metal  may  be  easily  torn  by 


THE  BUILDING  OF  SHIPS 


215 


the  backing  out  punch,  as  shown.  Sometimes  a  chipping 
tool  is  used,  and  sometimes  the  oxy-acetylene  blow  pipe 
or  cutter,  for  cutting  out  such  rivets,  but  both  methods 
must  be  used  with  great  care,  or  otherwise  the  metal  around 
the  rivet  holes  is  liable  to  be  damaged. 

The  diameter  of  a  rivet  hole  should  be  about  He"  greater 
than  the  diameter  of  the  cold  rivet.  This  allows  for  the 
insertion  of  the  hot  rivet  which  is  slightly  enlarged  by  the 
heating.  The  rivets  most  used  in  merchant  ship  'building 
are  %" ,  %" ',  %",  and  I".  In  naval  work  the  smaller 
sizes  (M">  %">  and  /4")  are  sometimes  used,  especially 
for  vessels  of  light  scantlings,  like  destroyers.  Rivets  as 
large  as  \%"  or  1J4"  are  required  only  for  very  large 


king-out 
Punch 


FIG.  95.  —  Cutting  out  rivets. 

ships  or  in  special  cases.  The  diameters  of  rivets  to  be 
used  should  be  selected  to  suit  the  thicknesses  of  the  plates 
or  shapes  that  they  are  to  connect.  The  practice  varies 
slightly  in  merchant  and  naval  work  but  the  following  is 
a  rough  guide  for  either  class  : 


10  Ib.  plate 
15  Ib.  plate 
20  Ib.  plate 
25  Ib.  plate 
30  Ib.  plate 
40  Ib.  plate 


in..  rivets 
in.  rivets 
in.  rivets 
in.  rivets 
in.  rivets 
in.  rivets 


Where  the  two  thicknesses  to  be  connected  vary  slightly 
the  size  of  rivet  should  correspond  to  the  greater  thickness 
if  strength  is  more  important,  and  to  the  lesser  thickness  if 


216  PRACTICAL  SHIP  PRODUCTION 

water  tightness  is  more  important.  If  the  two  thicknesses 
vary  greatly  the  diameter  of  the  rivet  should  correspond  to 
the  average  of  the  two.  The  increase  in  diameter  of  a 
punched  hole  due  to  subsequent  reaming  should  be  about 

y&". 

Hand  riveting  when  done  by  skilled  riveters  is  superior 
to  machine  riveting  but  is  more  expensive.  There  are  two 
riveters  in  a  hand  gang,  each  with  a  hammer,  striking 
alternate  blows  on  the  point  of  the  rivet.  One  works  right 
handed  and  the  other  left  handed.  Long  through  rivets 
such  as  those  through  stem,  stern  post  and  bar  keel  are 
usually  driven  by  hand. 

Such  rivets  are  heated  only  at  their  points,  the  main 
portion  of  the  shank  being  a  driving  fit  in  the  hole,  since  it 
is  practically  impossible  to  drive  them  tight  otherwise, 
and  also  since  the  contraction  on  cooling  of  a  long  rivet 
might  cause  it  to  break.  The  point  must  be  slightly 
tapered  before  it  is  inserted  in  the  hole  on  account  of  its 
enlargement  due  to  heating.  The  head  may  be  heated 
by  a  torch  and  well  staved  up  while  hot. 

Some  shipyards  that  build  very  large  vessels  employ 
portable  hydraulic  riveting  machines.  These,  on  account  of 
the  high  steady  pressure  that  can  thus  be  applied  to  the  rivets, 
produce  a  very  high  quality  of  work,  and  insure  the  com- 
plete filling  of  the  holes  by  the  rivets,  a  thing  that  is  very 
difficult  to  accomplish  by  hand  in  the. case  of  large  rivets. 

Tap  rivets  are  used  in  places  where  it  is  not  practicable  to 
drive  ordinary  or  through  rivets.  A  tap  rivet  is  really 
nothing  but  a  threaded  bolt  having  a  head  shaped  like  a 
rivet  head.  In  Fig.  96  are  shown  two  forms  of  tap  rivets. 
One  has  a  square  head  which  is  cut  off  after  it  has  been  well 
screwed  up.  The  other  has  a  "wring-off"  head  which  is 
twisted  off,  by  the  Stillson  wrench  with  which  it  is  screwed 
up,  as  soon  as  it  has  drawn  the  plating  up  tight  and  cannot 
turn  further. 

Tap  rivets  generally  have  to  be  used  to  a  certain  extent 
for  connecting  the  shell  plating  to  stem,  stern  frame,  and 
shaft  brackets,  and  in  other  similar  cases  where  a  thin  part 


THE  BUILDING  OF  SHIPS 


217 


is  connected  to  a  relatively  thick  one,  that  does  not  permit 
of  through  riveting.  They  should  not  be  used  in  thin  plat- 
ing since  the  threaded  portion  is  not  enough  in  such  cases 
to  give  good  holding  power.  The  depth  of  the  threaded 
portion  of  the  hole  should  be  at  least  equal  to  the  diameter. 
In  places  where  vibration  will  occur  (as  in  the  case  of  the 
propeller  boss)  a  depth  of  1%  diameters  should  be  required. 
The  holes  must  of  course  be  drilled,  and  both  the  drilling 
and  tapping  must  be  done  very  carefully  in  order  that  the 
head  may  fit  the  countersunk  hole  exactly  and  concen- 


Square  head,  to 
be  chipped  of 


Round  "wring- off' 
head          / 


FIG.  96.— Tap  rivets. 

trically  in  order  to  draw  the  two  parts  tightly  together. 
Sometimes  after  a  tap  rivet  has  been  screwed  up  and 
trimmed  off  the  head  is  heated  by  a  torch  and  driven  up 
by  a  riveting  hammer  so  as  to  fill  the  hole  tightly. 

Tack  rivets  are  rivets  located  in  the  middle  portions  of 
doubling  plates  so  as  to  keep  the  faying  surfaces  together 
at  all  points. 

For  oil-tight  work  an  especially  high  class  of  riveting  is 
necessary.  The  rivets  are  more  closely  spaced  (3  to  3K 
diameters  between  centres,  as  compared  to  water-tight 
spacing  which  is  usually  from  3>i  to  5  diameters),  and 
should  be  either  drilled  or  punched  small  and  reamed 
absolutely  fair. 

In  connecting  high  tensile  steel  plates  or  shapes  high 
tensile  rivets  should  be  used.  The  holes  should  be  drilled. 


218  PRACTICAL  SHIP  PRODUCTION 

Before  rivets  are  driven  the  following  points  should  be 
looked  out  for : 

1.  The  holes  should  be  properly  located,   fair,   of  the 
proper  size,  and  reamed  if  necessary. 

2.  The  plates  or  shapes  to  be  riveted  should  be  smooth, 
fair,  free  from  bumps,  knuckles,  burrs,  etc.,  and  securely 
drawn  together  with  a  sufficient  number  of  bolts,  well  set 
up.     (About  every  fourth  hole  for  oil -tight  work.) 

3.  There  should  be  no  chips,  shavings  or  other  foreign 
matter  between  the  faying  surfaces,  and  these  surfaces 
should  be  properly  coated — usually  with  red  lead,  if  for 
a  water-tight  or  non water- tight  joint,  or  with  a  mixture 
of  pine  tar  and  shellac  or  other  suitable  coating,  if  for  an 
oil -tight  joint. 

4.  If  for  oil-tight  work,  three-ply  work,  or  work  where 
strength  is  very  important,  the  holes  should  be  drilled  or 
punched  small  and  reamed  fair  and  normal  to  the  faying 
surface. 

5.  All  butts  and  edges  should  fit  tightly  together. 

6.  The  joints  should  be  metal-to-metal   and  filling-in 
pieces  should  not  be  used.     (In  certain  cases,  where  oil- 
stops  or  stop- waters  are  required,  these  should  be  in  place.) 

During  the  riveting  the  following  should  be  looked  out 
for: 

1.  The  rivets  to  be  used  should  be  long  enough  to  allow 
for  the  metal  required  for  forming  the  points. 

2.  The  rivets  should  be  of  the  proper  diameters  com- 
pletely to  fill  the  holes. 

3.  Care  must  be  used  to  see  that  the  rivets  are  not  sub- 
jected to  too  great  a  heat  and  thus  " burned. " 

4.  The  rivets  must  be  sufficiently  heated  (until  just  before 
they  give  off  sparks)  before  being  passed  to  the  holder-on. 

5.  The  heads  should  be  well  jammed  up  against  the  sur- 
face by  the  holder-on  before  the  riveter  strikes  the  points. 

6.  The  hole  must  be  completely  filled  by  driving  the  hot 
rivet  well  home. 

7.  The  excess  metal  from  the  point  should  be  cut  off 
while  it  is  a  dull  red.          -        - •-    -  -  '--  -  -  - 


THE  BUILDING  OF  SHIPS  219 

8.  The  point  should  be  properly  formed  and  concentric 
with  the  shank  of  the  rivet. 

9.  In  removing  bolts  care  should  be  taken  that  the  faying 
surfaces  do  not  spring  apart. 

10.  The  plates  or  shapes  around  the  rivet  holes  must 
not  be  dented  or  cut  during  the  riveting  or  chipping  off 
of  the  excess  metal  from  the  points. 

11.  If  a  rivet  is  not  driven  tightly  this  should  not  be 
concealed  by  a  partial  calking  of  the  head  or  point.     All 
riveting  should  be  carefully  and  conscientiously  done. 

In  general  the  effort  should  be  to  secure  riveted  joints 
that  are  in  strict  accordance  with  the  plans,  or  that  will 
develop  the  strength  and  water- tightness  that  they  are 
intended  to  develop.  All  the  rivets  should  be  of  the  proper 
size,  shape,  location  and  tightness,  holding  the  faying 
surfaces  closely  together — like  the  rivets  shown  in  Figs.  21 
and  96,  and  not  like  those  in  Figs.  89  and  92. 

4.  CHIPPING,  CALKING,  ETC. 

Chipping  consists  in  cutting  or  trimming  various 
structural  parts  by  means  of  a  chipping  tool  or  chisel. 
Like  riveting  it  may  be  done  by  hand,  or  by  means  of  a 
pneumatic  chipping  hammer,  the  action  of  which  is  similar 
to  that  of  the  pneumatic  riveting  hammer.  Chipping 
is  often  necessary  to  remove  burrs  or  other  unevennesses 
or  to  smooth  up  work  in  order  to  obtain  a  satisfactory  fit. 
Certain  large  holes  are  also  often  cut  out  by  the  chippers, 
especially  where  neat  work  is  required,  and  the  oxy- 
acetylene  blow-pipe  (which  is  much  quicker,  but  which 
leaves  a  rough  edge)  cannot  be  used.  Chippers  are  also 
employed  in  cutting  out  defective  rivets  or  other 'structural 
parts  that  have  to  be  removed,  although  much  work  of 
this  nature  is  now  done  by  the  oxy-acetylene  cutters. 

Calking  is  the  process  of  making  joints  tight  to  prevent 
the  leakage  of  water,  oil,  air,  etc.,  and,  in  the  case  of  steel 
parts,  consists  in  forcing  the  edges  or  butts  of  adjoining 
members  tightly  together.  It  is  usually  done  by  the  same 


220 


PRACTICAL  SHIP  PRODUCTION 


workmen  who  do  chipping  and  most  frequently  is  done  with 
pneumatic  tools  in  a  manner  similar  to  chipping.  Work- 
men of  this  trade  are  often  called  chippers  and  calkers. 

The  process  of  calking  is  illustrated  in  Fig.  97.  It 
consists  essentially  of  two  operations:  first  the  metal  is 
split,  or  grooved,  by  means  of  a  splitting  tool  or  splitter, 
and  then  the  portion  of  the  metal  between  the  split  and  the 
faying  surface  or  butt  is  forced  tightly  against  the  other 


Splitting 


Edge  Calking 


Calking  a  Lap  Joint 
(Edge  Calking) 


Calking  a  Butt  Joint 

(Butt  Calking) 
FIG.  97.— Calking. 


part,  as  shown  in  the  sketches,  by  means  of  the  calking  tool, 
or  finishing  tool.  There  are  two  kinds  of  calking:  edge  calk- 
ing, and  butt  calking,  the  nature  of  each  of  which  will  be 
evident  from  Fig.  97.  In  edge  calking  a  slight  shoulder  is 
formed,  as  shown,  where  the  edge  of  the  outer  plate  overlaps 
the  inner.  Countersunk  points  of  rivets  should  usually  be 
calked,  the  process  being  similar  to  butt  calking,  but  done 
with  a  special  small  ended  tool. 

Calking  is,  of  course,  not  done  until  after  the  riveting 
has  been  completed — the  order  of  the  various  processes 


THE  BUILDING  OF  SHIPS  221 

being:  (1)  bolting  up,  (2)  drilling  or  reaming  (and,  if 
necessary,  countersinking),  (3)  riveting,  (4)  calking.  The 
edges  and  butts  to  be  calked  should  be  planed.  The  row 
of  rivets  nearest  to  the  calking  edge  or  butt  serves  to  hold 
the  plates  (or  parts  being  riveted)  together  so  that  the 
calking  will  be  effective,  the  elasticity  of  the  steel  resulting 
in  keeping  the  outer  plate  pressed  tightly  against  the  inner 
at  the  calking  edge  after  the  calking  has  been  completed. 
For  this  reason  it  will  be  noted  that  the  line  of  the  rivets, 
must  not  be  too  far  from  the  calking  edge,  or  the  calking 
may  open  on  account  of  the  spring  of  the  plate.  On  the 
other  hand  the  rivets  must  not  be  too  close  to  the  edge  of 
the  plate  or  the  strength  of  the  joint  will  be  impaired. 
Furthermore  a  certain  allowance  must  be  made  for  cor- 
rosion and  for  repeated  calking,  as  certain  seams  may 
have  to  be  re-calked  from  time  to  time  in  the  course  of 
repairs  and  upkeep.  Each  re-calking  reduces  the  distance 
between  the  edge  of  the  plate  and  the  outer  row  of  rivets, 
which  distance  may  finally  become  so  small  as  to  require 
renewal  of  the  plate  (or  shape).  For  these  reasons  the 
distance  from  the  edge  of  the  plate  to  the  line  of  centres 
of  the  nearest  row  of  rivets  is  usually  made  equal  to  1J£ 
or  1%  times  the  diameter  of  the  rivets.  This  gives  an 
amount  of  plate,  between  rivet  and  edge,  of  at  least  the 
diameter  of  the  rivet. 

Any  line  of  calking  must  be  continuous — that  is  it 
must  either  join  another  line  of  calking  or  form  a  closed 
loop.  If  the  calking  stops,  or  is  defective  at  any  point, 
a  leak  will  occur  at  that  point,  and  the  good  of  the  remain- 
der of  the  calking  will  be  offset  by  this  one  point  of  weakness. 
The  calking  of  a  bulkhead,  or  other  plated  surface,  forming 
the  boundary  of  a  compartment  that  is  to  be  filled  with 
water  in  order  to  test  the  calking,  should  be  done  on  the 
side  away  from  this  compartment  in  order  that  such  leaks 
as  occur  may  be  located  during  the  testing,  and  repaired. 

Edges  and  butts  that  are  to  be  calked  should  have  a 
tight  metal-to-metal  fit  even  before  being  calked.  In 
some  cases,  especially  around  stapling  and  collars  this  is 


222  PRACTICAL  SHIP  PRODUCTION 

very  difficult  to  attain,  and  in  order  to  secure  a  proper 
calking  edge  the  use  of  metal  filling-in  pieces  or  wedges 
(sometimes  called  l ' dutchmeri")  may  be  permitted.  This 
is,  however,  a  bad  practice  and  should  be  avoided  by  in- 
sisting upon  careful  workmanship  of  the  anglesmiths  and 
shipfitters. 

Butt  calking  is  more  difficult  to  perform  than  edge 
calking  since  in  the  latter  the  inner  plate  serves  as  a  guide 
for  the  calking  tool,  whereas  in  the  latter  there  is  no  guide. 
In  some  places  calkers  have  to  work  "left-handed. " 

Light  plating  (less  than  about  JK6  mcn  thick)  cannot  be 
calked  since  there  is  not  sufficient  stiffness  to  the  material 
to  hold  the  calked  edges  together.  Here  stopwaters 
must  be  used. 

Stopwaters  (or  oil-stops)  must  also  be  used  where  an  un- 
calked  member  passes  through  a  water-,  or  oil-tight  surface, 
to  prevent  leakage  past  the  surface  through  the  parts  of  the 
uncalked  member.  Stopwaters  are  pieces  of  canvas,  bur- 
lap, felt,  etc.,  soaked  in  linseed  oil  and  red  lead,  or  coated 
with  some  tarry  substance  or  with  a  mixture  of  red  and 
white  lead.  These  are  placed  between  the  faying  surfaces 
which  are  drawn  tightly  against  them  by  the  rivets.  Oil- 
stops  are  made  of  lamp  wick,  canvas,  felt,  etc.,  soaked  in  a 
mixture  of  shellac  and  white  or  red  lead,  or  of  pine  tar  and 
shellac,  or  other  suitable  substance.  Oil-stops  are  used  to 
prevent  the  leakage  of  oil  and  must  therefore  be  treated 
with  some  substance  that  wilt  not  be  dissolved  by  oil.  Both 
oil-stops  and  stopwaters  should  be  used  only  where  abso- 
lutely necessary  and  they  should  be  freshly  coated  when 
the  bolting  up  and  riveting  is  done. 

Sometimes  leaky  joints  are  made  tight  by  welding, 
which  is  described  in  Section  6,  below. 

In  some  cases  where  joints  cannot  be  made  tight  by  calk- 
ing it  is  the  practice  to  make  use  of  the  red  lead  putty  gun. 
When  this  has  to  be  done  it  is  always  a  sign  of  poor  work- 
manship and  its  use  should  be  avoided  as  much  as  possible. 
This  contrivance  is  shown  in  Fig.  98,  and  consists  of  a 
simple  hollow  cylinder  threaded  on  the  inside,  which  is 


THE  BUILDING  OF  SHIPS 


223 


filled  with  red  lead  putty  and  connected  to  the  part  to  be 
gunned  as  shown  in  the  sketch.  As  the  plug  is  screwed 
down  the  putty  is  forced  into  the  joint  under  great  pressure 
and  fills  all  the  crevices.  When  this  operation  is  completed 
the  gun  is  unscrewed  and  the  hole  temporarily  made  for 
its  attachment  is  closed  by  means  of  a  threaded  plug, 
calked  in. 

Other  means  of  stopping  leaks,  such  as  the  use  of  shellac, 
cement,  etc.,  should  not  be  permitted. 


Head  of  plug- 


Threaded  plug- 


*  O^ 

Portable  lever 
\                   or  handle 

^  Holes  for  handle 

^Hollow  cylinder 


This  space  filled 


with  red  lead  putty 


Space  between 

improperly  fitted  plates 

to  be  gunned. 


'This  hole  plugged  after 
gunning  is  completed. 

FIG.  98. — Red  lead  putty  gun. 

Calking  is  tested  by  filling  the  compartment  adjacent, 
with  water  (to  a  head  corresponding  to  that  pressure  to 
which  the  bulkheads  or  other  boundaries  may  be  subjected), 
or  with  air  under  a  corresponding  pressure — if  with  water, 
leaks  can  be  seen  directly;  if  with  air,  soapy  water  rubbed 
along  the  calking  edges  will  cause  bubbles  to  appear  at  leaky 
points.  The  necessary  head  for  a  water-pressure  test 
may  be  secured  by  the  use  of  a  stand-pipe. 


224  PRACTICAL  SHIP  PRODUCTION 

A  surface  which  is  properly  calked  should  be  equally 
tight  when  subjected  to  pressure  from  either  side,  but  to 
be  properly  calked  all  of  the  calking  should  be  done  on  one 
side,  or  on  both  sides. 

Calking  of  oil-tight  work  is  especially  important,  and 
should  be  painstakingly  and  conscientiously  done. 

6.  PROTECTION  AGAINST  CORROSION 

In  order  to  be  able  to  have  a  ship  carry  as  great  a  weight 
of  cargo,  fuel,  machinery,  etc.,  as  possible,  the  weight  of  the 
hull  must  be  kept  low.  For  this  reason  the  thicknesses 
and  sizes  of  the  various  structural  members  should  be  no 
greater  than  is  necessary  to  secure  the  requisite  strength. 
In  almost  all  ships,  however,  the  thicknesses  of  the  struc- 
tural plates  and  shapes  are  made  somewhat  greater  than 
necessary  for  strength  alone,  in  order  to  provide  against 
the  effects  of  corrosion. 

Corrosion  is  the  process  of  gradually  wasting,  or  being 
eaten  away,  of  steel  or  iron.  It  may  occur  uniformly,  or 
may  be  more  rapid  in  certain  spots,  in  which  latter  case  it 
is  sometimes  called  pitting.  Steel  usually  corrodes  some- 
what faster  than  iron.  Corrosion  may  be  caused  either 
by  (1)  rusting  or  (2)  galvanic  action,  although  it  is  usually 
due  to  a  combination  of  both.  (Occasionally  corrosion 
is  caused  by  the  action  of  acids,  as  in  coal  bunkers,  or  where 
ashes  come  in  contact  with  steel.) 

Rusting  is  the  oxidation  of  the  iron  and  steel  when  in 
contact  with  carbon  dioxide,  or  CO2.  Although  commonly 
supposed  to  be  caused  by  moisture,  this  ig  not  strictly  true, 
since  moisture  alone  is  not  sufficient.  Iron  or  steel  placed 
in  pure  water  or  pure  air  will  not  rust,  but  practically  speak- 
ing water  and  air  both  always  contain  a  certain  percentage 
of  C02,  so  that  some  corrosion  will  always  occur  unless 
the  surface  of  the  iron  or  steel  is  properly  protected,  by 
some  suitable  coating,  from  the  action  of  CO2.  Corrosion 
is  much  more  rapid  when  heat  is  present. 

Galvanic  action  is  the  flow  of  an  electric  current  between 


THE  BUILDING  OF  SHIP  225 

two  dissimilar  metals  immersed  in  an  acid  and  in  metallic 
contact.  One  of  the  dissimilar  metals  will  always  be  elec- 
tropositive to  the  other  so  that  current  will  flow  through 
the  acid  from  the  former  to  the  latter,  and  this  flow  of 
current  is  accompanied  by  a  gradual  wasting  away  of  the 
metal  that  is  electropositive  to  the  other.  Sea  water,  which 
contains  various  salts,  acts  like  the  acid  of  an  electric  cell, 
and  if  two  different  metals,  for  example  copper  and  steel, 
are  in  metallic  contact  in  it,  one  of  them  (in  this  case  the 
steel)  will  gradually  be  eaten  away.  If  zinc,  which  is 
electropositive  to  steel  be  placed  near  the  copper  the  current 
will  flow  from  the  zinc  and  it,  instead  of  the  steel,  will  be 
eaten  away.  A  common  method  of  preventing  corrosion 
of  the  bottom  of  a  steel  ship  due  to  galvanic  action  is  there- 
fore to  place  slabs  or  rings  of  rolled  zinc,  called  zinc  pro- 
tectors, or  "zincs"  on  the  hull  at  points  near  propellers,  stern 
tube  bushings,  gudgeons,  valves  and  other  under-water 
fittings  that  are  made  of  bronze,  brass  or  similar  composi- 
tions. Zincs  are  secured  by  screws  or  stud  bolts  and  nuts. 
Also,  where  possible,  brass  or  bronze  should  be  insulated  or 
covered  with  some  non-conducting  material.  (Holes  over 
the  heads  of  brass  bolts  in  composite  or  sheathed  ships  are 
filled  in  with  Portland  cement.) 

It  should  be  noted  that  galvanic  action,  in  general,  occurs 
only  below  the  water  line,  whereas  rusting  may  take  place 
anywhere.  As  a  matter  of  fact  rusting  is  most  rapid  along 
the  water-line  portion  of  the  shell  plating,  which  is  al- 
ternately immersed  and  dried,  or  is  "  between  wind  and 
water,"  and  also  under  boilers,  where  the  temperature  is 
high. 

Galvanic  action  may  be  caused  by  impurities  in  steel  or 
by  variations  in  its  molecular  composition.  For  example 
rust  which  is  electronegative  to  steel  will  cause  the  steel 
to  corrode  away  and  the  points  of  rivets  which  are  affected 
by  the  hammering  given  them  when  driven  will  corrode 
away  more  slowly  than  the  adjacent  shell  plating. 

The  various  coatings  that  may  be  applied  to  steel  to 

15 


226  PRACTICAL  SHIP  PRODUCTION 

protect  it  from  the  action  of  CO2,  and  consequent  rusting, 
are  as  follows: 

(1)  Galvanizing. 

(2)  Various  kinds  of  paints  or  varnishes. 

(3)  Portland  cement. 

(4)  Various  bitumastic  and  other  special  compositions. 
Galvanizing  consists  in  coating  the  outer  surface  of  steel  or 

iron  plates,  shapes,  castings,  or  forgings  with  a  thin  layer  of 
zinc.  This  may  be  done  by  dipping  the  parts  in  a  bath  of 
molten  zinc  or  by  the  electrolytic  or  deposition  process. 
The  former  is  more  generally  used.  The  thin  plates  of 
destroyers,  where  saving  of  weight  and  consequent  small 
margin  against  corrosion  are  important,  are  usually  gal- 
vanized, as  are  most  small  iron  and  steel  deck  fittings  such 
as  rails,  stanchions,  ventilators,  cleats,  bitts  and  other 
such  parts  that  are  exposed  to  the  weather,  on  all  ships. 

Paints  and  varnishes  have  been  discussed  in  Section  5  of 
Chapter  II.  It  is  very  important,  in  applying  any  kind  of 
a  paint  or  other  coating  to  iron  or  steel,  that  the  surface 
be  absolutely  clean,  dry  and  free  from  rust,  oil,  or  any  other 
foreign  matter.  The  object  to  be  achieved  is  to  secure  an 
absolutely  perfect  adherence  of  the  paint  to  the  pure  iron 
or  steel  material,  and  this  cannot  be  accomplished  if  mois- 
ture, grease,  rust,  etc.,  are  present.  If  surfaces  are  properly 
prepared  before  paints  are  applied  the  results  will  be  much 
more  satisfactory.  Owing  to  the  difficulty  of  so  preparing 
these  surfaces,  entirely  satisfactory  painting  is  seldom 
secured  in  practice,  but  it  is  very  important  that  it  should 
be,  and  it  should  always  be  aimed  at.  Rust  under  paint  is 
often  worse  than  if  the  surface  were  left  bare,  for  it  thus  can 
go  on  unobserved. 

Portland  cement  is  used  to  form  passage  ways  for  the 
pumping  and  drainage  of  water,  oil,  etc.,  and  in  such  places 
as  wash  rooms,  water  closets,  etc.,  being  then  often  used  in 
conjunction  with  tiling. 

Bituminous  compositions  are  used  very  considerably  for 
the  various  ballast  and  trimming  tanks,  coal  bunkers, 
bilges,  etc. 


THE  BUILDING  OF  SHIPS  227 

The  efficacy  of  both  cement  and  bitumastics  (as  of  paints) 
is  in  great  measure  dependent  upon  the  care  with  which 
the  surfaces  have  been  prepared. 

During  the  building  of  a  ship  it  is  especially  important 
that  all  faying  surfaces  are  properly  cleaned  and  painted 
before  the  parts  are  finally  bolted  up  for  riveting.  Also 
the  removal  of  mill  scale  by  pickling  or  other  suitable 
means  and  the  proper  application  of  a  priming  coat  of  red 
lead  on  all  exposed  parts  are  important. 

(In  connection  with  the  subject  of  means  taken  to  pre- 
vent corrosion  see  also  Chapter  II,  Section  5.) 

6.  WELDING 

Although  welding  up  until  very  recently  has  been  used 
almost  solely  for  repair  work  (and  for  such  joining  of  parts 
as  is  incident  to  the  making  of  forgings)  it  has  during  the 
year  1918  become  developed  to  such  an  extent  that  it  has 
actually  been  used  for  joining  the  various  parts  of  a  ship 
together,  or,  in  fact,  replacing  riveting.  A  few  facts  con- 
cerning welding  should  therefore  be  noted. 

Welding,  proper,  consists  in  joining,  under  pressure,  two 
pieces  of  metal  that  have  been  heated  to  a  plastic  con- 
dition, and  as  such  is  exemplified  in  ordinary  blacksmith  or 
forge  work.  Soldering  consists  in  joining  metal  parts  by 
means  of  an  independent  alloy  which  is  fused,  or  melted 
and  applied  to  them.  A  solder  may  thus  be  called  a  metallic 
cement.  Autogenous  soldering  is  the  process  of  joining  two 
metal  parts  by  the  fusing  of  a  portion  of  some  of  their 
own  material,  and  the  term  " welding"  is  now  applied  to 
autogenous  soldering  as  well  as  to  ordinary  smith  welding. 

The  heating  of  the  parts  to  be  welded  in  the  case  of  or- 
dinary pressure  welding  may  be  accomplished  either  in  a 
forge  or  furnace  (in  which  case  the  pressure  is  usually  ap- 
plied by  means  of  hammering)  or  by  the  resistance  of  an 
alternating  electric  current  (the  parts  being  then  joined 
by  being  clamped  or  similarly  pressed  together).  An 
example  of  this  form  of  welding  is  what  is  known  as  spot 


228  PRACTICAL  SHIP  PRODUCTION 

welding  which  gives  a  finished  product  somewhat  re- 
sembling one  that  has  been  flush  riveted. 

The  principal  forms  of  fusion  welding  are  by  means  of  the 
oxy-acetylene  or  oxy-hydrogen  torch,  "Thermit"  welding 
and  electric  welding. 

Oxy-acetylene  and  Oxy-hydrogen  Welding. — In  this 
process  a  blow-pipe  or  torch,  is  used  to  heat  the  surfaces 
to  be  welded  to  the  fusing  temperature.  Oxygen  and 
some  combustible  gas  (acetylene,  hydrogen,  coal  gas,  etc.) 
are  supplied  to  the  blow-pipe  from  large  flasks  or  cylinders 
by  means  of  separate  lengths  of  rubber  hose  fitted  with 
suitable  valves  for  adjusting  the  pressures.  The  oxygen 
and  acetylene  (or  other  gas)  are  combined  in  a  mixing 
chamber,  which  is  part  of  the  torch,  and  the  mixture  is 
forced  out  of  a  small  tuyere  or  nozzle  at  the  end  of  the  torch, 
and  when  ignited  gives  a  flame  of  intense  heat.  Metal  is 
gradually  added  to  the  junction  of  the  parts  to  be  connected 
and  the  weld  thus  built  up. 

This  process  of  welding  is  applicable,  in  general,  only  to 
relatively  small  parts  and  for  the  welding  of  large  parts 
that  have  been  broken,  such  as  stem  and  stern  castings, 
electric  welding  is  more  satisfactory. 

A  modification  of  the  oxy-acetylene  blow-pipe,  in  the 
tip  of  which  are  several  orifices  or  tuyeres,  is  used  for  cutting. 
The  central  orifice  provides  passage  for  a  jet  of  pure  oxygen 
called  the  cutting  oxygen,  and  the  outer  orifices  carry 
jets  of  the  mixture  of  oxygen  and  combustible  gas,  called 
the  preheating  gas. 

Thermit  welding  consists  in  placing  a  mixture  of  aluminum 
and  oxide  of  iron  (Fe2Os)  in  a  crucible  over  the  parts  to  be 
welded,  which  are  surrounded  by  a  built  up  mold  of  re- 
fractory material  after  having  been  securely  fixed  in  posi- 
tion. When  the  mixture  is  ignited  a  very  high  temperature 
is  obtained  and  the  melted  iron,  being  allowed  to  run  into 
the  mold,  heats  the  parts  to  a  fusing  temperature  and 
amalgamates  with  them.  This  process  has  some  applica- 
tion to  the  repair  of  large  parts  like  stem  and  stern  frames, 


THE  BUILDING  OF  SHIPS  229 

but  has  not  always  been  entirely  satisfactory,  electric  weld- 
ing being  usually  preferred  to  it. 

Electric  Welding  (Fusion). — It  is  this  form  of  welding 
that  has  recently  come  into  such  general  use  for  ship  re- 
pairing and  shipbuilding  purposes  (as  well  as  many  others). 
The  parts  to  be  welded  are  brought  to  the  highest  known 
temperature  by  means  of  an  electric  current  which  forms 
an  arc  between  two  electrodes  located,  one  or  both,  at  or 
near  the  weld.  The  work  itself  usually  forms  one  elec- 
trode though  this  is  not  always  the  case.  Direct  current  is 
used,  generally  at  about  100  volts,  and  with  current  varying 
between  50  and  500  amperes.  Sometimes  a  carbon  elec- 
trode is  used  in  which  case  it  is  the  negative  one,  so  as  not 
to  carry  carbon  into  the  weld.  More  often  the  electrode  is 
a  slender  rod  or  pencil  of  a  composition  similar  to  the  parts 
to  be  welded  and  is  carried  in  an  insulated  holder  which  the 
operator  holds  in  his  hand.  It  then  forms  the  positive 
electrode  and  is  itself  deposited  in  the  weld  by  the  passage 
of  current  across  the  arc,  and  thus  forms  and  builds  up  the 
weld. 

Metal  electrodes  may  be  bare  or  coated  in  various  ways. 
In  the  Quasi-Arc  process,  used  for  ship  welding,  the  coating 
is  a  special  composition  which  melts  as  the  pencil  is  used  up 
and  forms  a  flux  which  covers  both  the  end  of  the  pencil 
and  the  molten  metal  deposited  in  the  weld,  thus  protecting 
them  against  oxidation. 

In  July  of  1918  the  Technical  Committee  of  Lloyd's 
Register  decided  that  the  application  of  arc  welding  to  use 
in  connecting  the  main  structural  members  of  ships  ap- 
peared to  be  justified,  although  qualifying  this  decision  by 
a  statement  to  the  effect  that  "the  application  should 
proceed  cautiously  in  view  of  the  unknown  factors  involved, 
the  most  important  of  which  are  the  need  of  experience 
with  the  details  of  the  welded  joints  and  the  necessity  for 
training  skilled  workmen  and  supervisors." 

Various  forms  of  welds  are  shown  in  Fig.  99.  The  width  of 
the  laps  varies  between  2  inches  for  16-lb.  plates  and  3  inches 
for  40-lb.  plates.  The  thickness  of  throat  of  a  full  weld  varies 


230 


PRACTICAL  SHIP  PRODUCTION 


between  K  inch  for  40-lb.  plates  and  0.28  inchfor  16-lb.  plates. 
For  lighter  plates  the  outer  surface  of  the  weld  is  practically 
flat  and  makes  an  angle  of  45°  with  the  plates.  The  full 
weld  is  of  course  the  strongest,  and  next  in  strength  is  the 
light  closing  weld.  Tack  welding  is  used  where  strength 


Weld 


I 


Thickness  of 
Throat 


FULL  WELD 


Full  Weld 
(Large) 


u 


Weld 


'LIGHT  CLOSING  WELD 


Weld, 


fel 


INTERMITTENT  OR  TACK.  WELD 

FIG.  99. — Electric  quasi-arc  welding. 

is  not  so  important,  only  about  33  per  cent,  of  the  length  of 
the  edge  being  welded  in  this  case. 

For  satisfactory  work  the  electrodes  must  be  of  uniform 
quality  and  the  relation  of  their  composition  to  that  of  the 
steel  plates  and  shapes  must  be  such  as  not  unduly  to  re- 
duce the  elasticity  of  the  whole  structure. 

The  size  of  the  electrode  and  the  amperage  must  be  ad- 


THE  BUILDING  OF  SHIPS  231 

justed  to  vary  directly  with  the  thickness  of  the  plate  or 
shape  to  be  welded. 

Skilled  workmanship  is  very  important  and  care  must  be 
exercised  to  prevent,  in  so  far  as  possible,  oxidation  of  the 
deposited  metal.  This  is  accomplished  by  means  of  the 
flux  formed  by  the  coating  of  the  electrode. 

The  faying  surfaces  must  be  accurately  fitted,  and  all 
butt  connections  must  be  strapped. 

Both  edges  of  plates  of  butts  of  shell  plating,  deck  and 
inner  bottom  plating,  and  plating  of  longitudinals,  girders 
and  hatch  coamings  should  be  connected  by  full  welds. 

A  full  weld  is  applied  to  the  outside  edge  and  a  light 
closing  weld  to  the  inside  edge  in  the  case  of  edges  of  shell, 
deck  and  inner  bottom  plating  and  butts  and  edges  of  bulk- 
head plating. 

Frames,  beams,  stiff eners,  etc.,  have  at  the  heel  a  light 
closing  weld,  and,  at  the  toe,  tack  welding.  All  water- 
tight angle  bars  have  continuous  welding  at  each  toe  with 
tack  welding  at  the  heel. 

The  great  advantages  of  welded  over  riveted  connections, 
such  as  saving  in  weight,  doing  away  with  the  need  for 
calking,  saving  in  labor  and  time,  etc.,  are  too  evident  to 
require  comment,  and  it  only  remains  to  be  seen  whether 
this  method  of  building  ships  will  prove  as  great  a  step  in 
advance  as  it  now  gives  promise  of  doing. 

7.  LAUNCHING 

When  the  under-water  shell  plating  has  been  riveted  and 
calked  and  the  progress  of  construction  of  the  ship  other- 
wise is  considered  sufficiently  advanced  she  is  launched. 
The  amount  of  work  done  previous  to  launching — like 
the  amount  done  before  the  laying  of  the  keel — may  vary 
between  wide  limits.  Where  a  yard  is  endeavoring  to 
build  a  number  of  ships  in  a  short  time,  so  that  the  keel 
for  one  will  be  laid  immediately  after  another  has  been 
launched,  it  is  an  advantage  to  launch  as  soon  as  possible. 
On  the  other  hand,  if  extreme  expedition  is  not  so  important, 


232  PRACTICAL  SHIP  PRODUCTION 

it  is  usually  advantageous  to  delay  the  launching  until  the 
hull  is  very  nearly,  if  not  entirely  completed.  When  the 
hull  is  on  the  building  slip  it  is  practically  rigid  (and  in 
some  yards  is  entirely  roofed  over)  so  that  it  can  be  more 
efficiently  worked  upon.  After  the  launching  the  ship 
may  roll  or  list  at  times,  thus  interfering  somewhat  with 
work,  and  furthermore  there  may  be  no  convenient  dock 
or  pier  at  which  to  moor  her  if  launched  too  soon. 

In  any  case  before  a  ship  is  launched  sufficient  work 
must  have  been  done  to  give  her  the  requisite  buoyancy, 
strength  and  stability  for  flotation,  and  such  parts  as  will 
be  inaccessible  for  work  on  them  with  the  vessel  in  the  water 
must  have  been  completed,  unless — as  may  be  sometimes 
the  case  for  special  reasons — she  is  to  be  placed  in  dry- 
dock  prior  to  final  completion.  These  parts  include  rudder, 
struts,  propeller  shafts  and  propellers,  bilge  and  docking 
keels  and  various  other  miscellaneous  underwater  fittings. 

During  the  building  of  a  ship  a  careful  record  should  be 
kept  of  the  locations  and  weights  of  all  parts  worked  into 
the  hull.  With  this  data  calculations  are  made,  shortly 
before  the  launching,  to  determine  what  will  be  the  exact 
launching  weight  of  the  ship  (or  her  displacement  when 
she  takes  the  water)  and  what  will  be  the  exact  location 
of  the  centre  of  gravity  of  the  ship,  as  launched. 

Certain  calculations  are  then  ordinarily  made  (unless  the 
ship  is  a  duplicate  of  another  already  satisfactorily  launched 
under  the  same  conditions)  to  see  that  the  ways  are  properly 
designed  to  prevent  any  accident  during  launching. 

The  principal  points  to  be  looked  out  for  in  designing 
and  preparing  the  ways  are  as  follows: 

1.  Bearing  pressure  on  ways. 

2.  Prevention  of  tipping. 

3.  Prevention  of  premature  pivoting. 

4.  Strength  of  ways  under  point  about  which  pivoting  will  occur. 

5.  General  details  of  ways,  cribbing,  shoring,  etc.,  to  give  sufficient 
strength  at  all  points. 

Some  of  these  points  have  been  discussed  in  Section  2, 
of  Chapter  V,  but  the  following  should  also  be  noted  here : 


THE  BUILDING  OF  SHIPS 


233 


Considering  the  ship  at  any  instant  during  the  launching, 
after  she  has  moved  a  certain  distance  down  the  ways,  the 
forces  acting  on  her  will  be,  as  illustrated  in  Fig.  100: 

1.  The  weight  of  the  hull,  W,  acting  vertically  downward 
through  the  centre  of  gravity; 

2.  The  force  of  buoyancy,  B,  acting  vertically  upward 
through  the  centre  of  buoyancy,  or  centre  of  figure  of  the 
immersed  portion  of  the  ship;  and, 


Centre  of  Gravity  of  Hull 


Water  Line 


End  of  Ways  (fulcrum  for.  Tipping) 


Fore  Poppets  (fulcrum  for  Pivoting) 


FIG.  100. — Forces  acting  on  ships  during  launching. 

3.  The  upward  vertical  support  or  reaction  of  the  launch- 
ing ways  which  may  be  considered  as  resolved  into  two 
parallel  compartments,  Q  and  R,  one  acting  through 
the  end  of  the  ways,  and  the  other  through  the  fore  poppets 
which  are  located  at  or  near  the  fore  foot,  and  are  the  points 
furthest  forward  at  which  the  hull  receives  any  support 
from  the  ways. 

Referring  again  to  the  figure  it  will  be  seen  that  at  the 
instant  represented  any  one  of  three  things  may  happen : 

(1)  If  the  moment  of  the  force  of  buoyancy,  B  about  the 


234  PRACTICAL  SHIP  PRODUCTION 

end  of  the  ways  is  equal  to  the  moment  of  the  weight,  W 
about  the  end  of  the  ways  (or  if  B  X  a  =  W  X  6),  the  ship 
will  tip,  and  at  that  instant  all  of  the  support  of  the  ways 
will  be  concentrated  at  their  end,  or  R  will  vanish,  and  Q 
will  be  equal  to  (W  —  B). 

(2)  If  the  moment  of  the  force  of  buoyancy,  B  about  the 
fore  poppets  is  equal  to  the  moment  of  the  weight,  W  about 
the  fore  poppets  (or  if  B  X  c  =  W  X  d),  the  ship  will  pivot, 
and  at  that  instant  all  of  the  support  of  the  ways  will  be 
concentrated  at  the  fore  poppets,  or  Q  will  vanish,  and  R 
will  equal  to  (W-B). 

(3)  If  neither  of  the  two  preceding  happens  the  ship  will 
continue  to  move  down  the  ways  until  one  or  the  other 
of  them  does  happen. 

By  calculating  the  values  referred  to  in  (1)  and  (2)  for 
several  different  assumed  positions  of  the  ship,  at  intervals 
during  her  movement  down  the  ways,  curves  may  be 
plotted,  having  for  abscissas  the  amounts  of  travel  of 
the  ship  from  her  initial  position,  and  for  ordinates  the 
corresponding  values  of  B,  (B  X  a),  (W  X  b),  (B  X  c)  and 
(W  X  d).  From  these  curves  the  point  at  which  tipping 
will  occur  (if  at  all),  the  point  at  which  pivoting  will  occur, 
and  the  reaction  of  the  ways,  in  either  case,  may  be  found 
graphically.  This  information  is  necessary  to  check  the 
length  of  the  ways,  and  their  declivity  and  strength,  the 
necessary  strength  for  the  fore  poppets,  and  the  point 
under  which  the  ways  should  be  reinforced  to  take  the 
pressure  of  the  fore  poppets  when  the  stern  lifts. 

In  finding  the  various  values  of  B,  and  the  locations  of  the 
line  through  which  it  acts,  it  is  convenient  to  draw  a  set  of 
curves  called  Bonjearis  Curves,  which  consist  of  a  curve 
drawn  for  each  frame  station  of  the  lines,'  the  abscissa 
of  which  at  any  height  above  the  base  line  equals,  to  scale, 
the  area  of  that  frame  station  up  to  that  height.  These 
curves,  used  in  conjunction  with  Simpson's  or  some  similar 
rule,  furnish  a  convenient  means  for  determining  successive 
values  of  B  and  a.  (In  making  these  calculations  the 


THE  BUILDING  OF  SHIPS  235 

height  of  the  tide  at  the  hour  set  for  launching  must  be 
taken  into  account.) 

The  fore  poppets  are  portions  of  the  crib  work  over  the 
forward  end  of  the  launching  ways,  one  under  each  bow 
of  the  ship.  Ordinarily  they  consist  merely  of  heavy 
timbers  built  up  in  a  manner  similar  to  the  rest  of  the  crib- 
bing, but  in  very  large  ships  they  may  be  made  in  the  form 
of  actual  trunnion  bearings,  constructed  of  steel  and  con- 
crete, with  trunnions  attached  to  the  hull. 

The  general  arrangement  of  the  standing  and  sliding 
ways  and  the  cribbing  is  shown  in  Fig.  71.  Shortly  before 
the  date  set  for  launching  the  standing  or  ground  ways 
are  laid  in  position  and  properly  blocked  up,  secured  and 
shored  to  prevent  spreading.  Their  upper  surfaces  are 
then  coated  with  some  suitable  launching  grease  (usually 
containing  tallow,  etc.),  and  the  sliding  ways,  their  lower 
surfaces  having  been  similarly  greased,  are  placed  in  posi- 
tion and  the  cribbing  which  is  to  transmit  the  weight  of 
the  hull  to  the  sliding  ways  is  installed,  loosely,  wedges 
between  it  and  the  sliding  ways  being  not  set  up. 

The  above  procedure  should  take  place  as  short  a  time 
before  the  launching  as  possible  in  order  to  prevent  the 
grease  from  melting  or  being  squeezed  out  from  between  the 
timbers.  During  this  time  the  hull  is  supported  by  the 
keel  blocks  and  by  shores  and  blocks  kept  clear  of  the 
launching  ways. 

On  the  day  of  the  launching  a  carefully  prepared  schedule 
of  operations  is  carried  out  and  all  arrangements  must  be 
made  in  advance  so  that  there  will  be  no  hitch,  and  so 
that  the  launching  will  take  place  with  the  desired  height 
of  tide.  A  large  gang  of  men  must  be  detailed  for  the 
wedging  up  and  other  tasks  incident  to  the  launching 
and  all  must  know  exactly  what  to  do  and  at  whose  order 
it  is  to  be  done.  Absolute  unity  of  action  is  necessary 
in  order  to  prevent  mishaps.  The  wedging  up  is  done  at 
the  word  of  the  official  in  charge  and  should  be  so  timed 
as  to  have  the  vessel  borne  by  the  ways  for  as  short  an  in- 
terval  as  possible  before  the  launching.  This  interval  must 


236  PRACTICAL  SHIP  PRODUCTION 

necessarily  be  the  time  necessary  for  splitting  out  or  other- 
wise removing  the  keel  blocks,  and  removing  shores, 
blocking  and  other  material  that  would  obstruct  the 
launching. 

When  the  word  to  wedge-up  is  given  all  the  workmen  as- 
signed to  that  duty  quickly  drive  home  the  wedges  so  that 
the  weight  of  the  hull  is  transferred,  as  much  as  possible, 
from  the  keel  blocks  and  shores  to  the  cribbing  and  launch- 
ing ways.  The  removal  of  the  keel  blocks  and  shores, 
etc.  (which  follows  the  wedging  up  as  rapidly  as  possible) 
completes  this  transfer,  so  that  the  entire  weight  is  finally 
taken  by  the  launching  ways  as  shown  in  Fig.  71.  (To 
facilitate  quick  removal  of  the  keel  blocks  they  are  some- 
times made  in  the  form  of  metal  boxes  containing  sand, 
and  so  constructed  that  the  sand  may  be  allowed  to  run 
out  and  the  load  thus  be  removed.) 

The  launching  is  accomplished  by  various  forms  of  re- 
leasing devices  or  triggers,  some  quite  elaborate  (such 
as  hydraulic  cylinders  and  pistons)  and  others  very  simple 
(such  as  two  pieces  of  timber  retaining  the  sliding  ways 
which  are  sawed  off  simultaneously.) 

Before  the  launching  the  ship  must  be  properly  shored 
internally'  to  take  any  stresses  that  are  anticipated  and 
her  stability  must  be  investigated,  suitable  ballast  being 
added  if  there  is  any  doubt. 

As  the  ship  slides  down  the  ways  considerable  momentum 
may  be  acquired  and  it  is  sometimes  necessary  to  provide 
means  for  checking  her  sternway  after  she  strikes  the  water. 
Means  for  doing  this  vary  with  the  conditions,  a  common 
one  being  to  have  heavy  cables  stopped  to  the  ship  at 
intervals,  the  stops  to  be  broken  by  the  momentum  which 
is  thus  gradually  destroyed.  Tugs  then  transfer  the  ship 
other  fitting  out  pier. 

The  launching  of  the  ship,  which  is  an  important  event 
in  her  production  is  almost  always  made  the  occasion  for  a 
suitable  ceremony  and  celebration.  As  the  ship  starts  to 
move  the  lady  chosen  as  her  sponsor  breaks  a  bottle  of 
champagne  over  the  bow  and  christens  the  ship.  For  this 


THE  BUILDING  OF  SHIPS  237 

purpose  a  large  platform  is  temporarily  built  up  just  forward 
of  the  bow,  supported  by  heavy  scaffolding,  and  surrounded 
by  a  stout  railing.  On  this  platform  are  stationed  the 
sponsor  and  the  launching  party.  After  the  ship  is  in 
the  water  a  luncheon  and  celebration  is  usually  given. 

8.  FITTING  OUT 

The  work  done  on  a  ship  after  she  has  been  launched 
and  before  she  is  finally  completed  and  delivered  to  the 
owner  consists,  in  general,  in  the  completion  of  the  struc- 
tural work  of  the  hull  that  was  not  accomplished  prior  to 
launching,  and  the  installation  of  various  piping,  ventila- 
tion, and  electrical  systems,  joiner  work,  deck  fittings, 
auxiliary  machinery,  engines  and  boilers  (if  not  installed 
before  the  launching),  smoke  stacks,  ventilators,  spars, 
rigging,  bridges,  deck  houses,  etc.,  and  a  great  variety  of 
other  miscellaneous  parts  and  trimmings. 

In  addition  to  this,  numerous  tests  must  be  made  to  see 
that  ,  everything  is  in  satisfactory  working  order,  the 
various  articles  of  equipment  must  be  supplied,  and 
the  hull  cleaned  and  freed  of  rubbish  and  other  foreign 
matter,  and  all  necessary  painting  done. 
•  The  greater  portion  of  this  work  covers  the  operations  of 
such  trades  as  those  of  the  plumbers,  pipe  fitters,  joiners, 
shipwrights,  riggers,  electricians,  machinists,  painters,  etc., 
and  a  full  discussion  of  the  various  details  involved  would 
occupy  too  much  space  to  be  undertaken  here.  It  is  really 
fitting  out,  rather  than  building,  a  ship;  and  a  large  part  of 
it  is  very  similar  to  work  done  by  the  same  trades  on  shore. 
Certain  important  points  that  apply  to  shipbuilding  in 
particular  should,  however,  be  noted. 

As  is  natural,  during  the  latter  stages  in  the  construction 
of  a  ship,  when  the  time  for  her  delivery  to  the  owners  is 
drawing  near,  it  is  important  to  check  up  and  see  if  all  of 
the  requirements  of  ships  (see  Chapter  I)  have  been 
complied  with. 

The  buoyancy  is,  of  course,  demonstrated,  in  general, 


238  PRACTICAL  SHIP  PRODUCTION 

by  the  fact  that  the  vessel  floats  after  launching  and  that 
she  has  been  built  in  accordance  with  the  plans.  Any 
leaks  that  develop  in  the  shell  plating  after  launching  will, 
of  course,  be  remedied  in  so  far  as  possible  when  noted, 
and  if  necessary  the  vessel  will  be  dry-docked  and  the 
leaks  calked. 

There  is  also  to  be  considered,  in  connection  with  the 
subject  of  buoyancy,  however,  the  question  of  integrity  of 
water-tight  subdivision.  A  portion  of  this  has  probably 
been  demonstrated  before  the  launching  by  tests  of  bulk- 
heads and  compartments  which  have  been  subjected  to 
a  sufficient  head  of  water.  During  the  last  stages  of  con- 
struction it  is  very  important  to  see  that  this  integrity  is 
not  destroyed  by  the  cutting  of  holes  in  bulkheads  and 
decks. 

It  is  practically  impossible  to  avoid  having  some  holes  in 
water-tight  bulkheads  and  decks,  both  for  doors,  manholes, 
etc.,  and  for  piping  and  wiring.  The  former  must  be  of  the 
water-tight  type,  and  wherever  a  water-tight  plated  surface 
is  pierced  by  a  pipe  or  conduit  the  construction  must  be  so 
arranged  as  to  prevent  the  passage  of  water  around  that 
pipe  or  conduit.  This  is  accomplished  by  the  use  of 
flanges  or  stuffing  boxes,  which  must  be  carefully  made  and 
installed  and  properly  packed  with  suitable  gaskets  or 
packing,  as  the  case  may  be.  Means  for  the  attachment 
of  brackets,  castings,  hangers,  etc.,  to  water-tight  members 
must  be  such  as  not  to  destroy  or  impair  their  water- 
tightness.  Constant  and  conscientious  supervision  is 
necessary  to  attain  these  results. 

Stability  depends  largely  upon  the  correct  execution  of 
design,  and  one  very  important  check  on  this  is  the  deter- 
mination of  the  actual  transverse  metacentric  height  of 
the  ship  by  means  of  an  inclining  experiment,  which  should, 
if  possible,  be  conducted  as  the  ship  is  nearing  completion. 

This  consists  in  heeling  the  ship  over  to  various  small 
inclinations  by  means  of  moving  heavy  weights  across 
the  decks  and  recording  the  amount  of  weight  moved,  the 
thwart  ship  distance  through  which  it  is  moved,  and  the 


THE  BUILDING  OF  SHIPS 


239 


angle  of  heel,  in  each  case.     The  displacement  is  also  care- 
fully noted. 

The  operation  is  illustrated  in  Fig.  101,  the  angle  of  heel, 
0,  being  measured  by  means  of  a  plumb  bob  and  graduated 
scale,  as  shown.  The  inclination,  6  is  in  this  case  pro- 
duced by  the  movement  of  the  weight,  w  a  distance,  /, 
transversely.  Let  W  be  the  total  displacement  of  the  ship, 
and  let  Gr  and  Bf  (which  must  be  in  the  same  vertical  line) 


FIG.  101. — Inclining  experiment. 

be  the  new  centres  of  gravity  and  buoyancy.     Then,  by 
taking  moments, 

W  XGG'  =  wX  I 
and 

GG'         wXl 


GM  = 


a 


tan  B  ~    W  tan  0 


but  tan  0  =  T  (which  has  been  recorded) 
w  XlXh 


aXW 

A  number  of  different  "check"  readings  are  taken  and  if 


240  PRACTICAL  SHIP  PRODUCTION 

these  all  agree  the  calculated  value  of  the  metacentric 
height,  GM,  may  be  assumed  to  be  fairly  accurate.  During 
the  experiment  the  ship  must  be  entirely  free  from  the 
action  of  any  external  force  or  forces,  and  there  must  be 
no  "  loose' '  weights  on  board — such  as  water  in  tanks  not 
completely  filled. 

The  longitudinal  metacentric  height  may  be  found  simi- 
larly and  this  is  usually  done  in  the  case  of  the  submerged 
inclining  experiment  of  a  submarine.  (In  this  connection 
it  should  be  noted  that  the  metacentre  of  a  submerged 
body  coincides  with  the  centre  of  buoyancy.) 

The  propulsion  of  the  ship  is  checked,  usually,  by  dock 
trialSj  and  a  trial  trip,  before  being  accepted  by  the  owners. 
Similarly  the  steering  gear  should  be  very  thoroughly  tried 
out  before  delivery  of  the  vessel.  These  are,  of  course, 
actual  operating  tests. 

Strength  must,  of  course,  depend  largely  upon  good 
workmanship  and  a  strict  compliance  with  the  plans  and 
specifications.  During  the  latter  stages  of  construction 
it  is  important  to  see  that  the  strength  is  not  impaired  by 
holes  or  notches,  etc.  cut  in  various  structural  members, 
during  the  installation  of  piping  systems  and  other  fittings, 
etc.  This  also  requires  careful  and  conscientious  supervi- 
sion. Holes  drilled  through  beams  should  be  near  the 
centre  or  in  the  upper  half  of  the  web  and  should  be  in  only 
one  horizontal  row.  The  diameter  of  such  holes  should 
not  be  over  about  20  %  of  the  depth  of  the  beam  and  holes 
should  not  be  too  close  together.  Whenever  alterations 
are  made  in  the  design  of  a  ship  during  the  building  great 
care  should  be  used  to  see  that  the  strength  is  not  there- 
by impaired.  As  has  been  said  before,  however,  honest, 
skillful,  conscientious  workmanship,  at  all  times,  is  of  fun- 
damental importance  in  securing  the  necessary  strength  in  a 
ship. 

Endurance  is  demonstrated  by  the  fuel  consumption  on 
the  trial  trip  and  a  checking  up  or  calibration  of  the  bunkers. 
This  consists  in  taking  accurate  measurements  of  coal 
bunkers  or  fuel  oil  tanks  and  calculating  their  capacities. 


THE  BUILDING  OF  SHIPS  241 

For  oil  tanks  it  is  done  by  filling  them  with  water  from  ac- 
curately graduated  measuring  tanks.  The  data  thus  ob- 
tained is  furnished  to  the  owners  with  the  ship. 

The  utility  of  the  ship  depends  upon  a  compliance  with 
the  plans  and  specifications.  During  the  latter  stages  of 
construction  care  should  be  exercised  to  see  that  the  mul- 
titudinous details,  all  of  which  make  for  utility,  are  looked 
out  for.  This  applies  also  to  living  spaces  and  accommo- 
dations and  similar  considerations  affecting  the  health 
and  comfort  of  the  crew  and  officers. 

Throughout  the  various  processes  of  ship  production  the 
objects  to  be  attained  should  always  be  kept  in  mind,  for 
it  is  only  by  knowing  what  is  wanted  that  it  can  ever  be 
completely  obtained.  Each  and  every  man  connected 
with  the  production  of  ships  should  realize  his  responsibili- 
ties, and  endeavor  conscientiously  to  see  that  his  part  of 
the  job  is  properly  done. 


16 


INDEX. 


Aft,  34 

After  peak  tank,  45 

After  perpendicular,  36 

Afterbody,  35 

Air  holes,  90 

American  Bureau  of  Shipping,  63 

Amidships,  34 

Anchor  windlass,  47 

Anchors,  47 

Angle  bar,  64 

in  frames,  79 
of  maximum  stability,  9 
of  vanishing  stability,  9 

Anglesmiths,  171 

Arc  welding,  229 

Area  of  wetted  surface,  143 

Armored  cruisers,  55 

Arrangement  of  a  ship,  41 

Asbestos  used  on  ships,  72 

Athwartships,  2,  34 

Atwood's  formula,  139 

Autogenous  soldering,  227 

Auxiliary  vessels,  57 

Average  secant,  144 

B 

Balanced  rudders,  21,  95 
Ballast,  47 
Bar  keels,  77 
Base  line,  31,  35 
Battens,  182 
Battle  cruisers,  55 
Battleships,  54 
Beam  knee,  114 
Beam  mold,  192 

of  ship,  2 
Beams,  deck,  114 


Beams,  fabrication,  192 
Belt  frames,  82 
Bending  frames,  168 

moment,  curve  of,  27 

slabs,  162 
Bevel  boards,  185, 188 

of  a  frame,  79,  83 
Beveling  bars,  191 

frames,  168 
Bibliography  of  naval  architecture, 

145 
Bilge,  39 

diagonal,  32 

keels,  128,  129 

keelsons,  83 

stringers,  85 
Bilges,  12 
Bitts,  127 

Bituminous  compositions,  73,  226 
Block    coefficient    of    fineness,    40, 

41 
Blow  pipe,  oxy-acetylene,  167 

used  in  welding,  228 
Boat  deck,  48 
Boatbuilders,  178 
Body  plan,  32 

post,  94 
Boiler  room,  46 
Boilers,  supporting,  125 
Bolsters,  127 
Bolters-up,  175 
Bolting  up  ship  frames,  206 
Bon  jean's  curves,  234 
Bosom  piece,  173 
Boss,  39 
Bossed  frames,  101 

plates,  107 
Bottom,  37 

double,  47,  85 

inner,  47,  106 
Bounding  bars,  122 


243 


244 


INDEX 


Bounding,  fabrication,  192 

of  deck  plating,  116 
Bow,  12,  39 

and  buttock  lines,  32 
Bracket  floors,  89 
Brackets,  83,  114,  173 
fabrication,  192 
shaft,  103 

Brass  in  ship  construction,  70 
Breadth,  molded,  36 
Breast  hooks,  27,  90 
Bridge,  48 

British  Corporation,  63 
Broadside  launching,  157 
Bronze  in  ship  construction,  70 
Building  ships,  195-241 
bolting  up,  204 
calking,  219 
chipping,  219 
drilling,  207 
erection,  195 
fitting  out,  237 
launching,  231 
protection  against  corrosion, 

224 

reaming,  205 
riveting,  209 
testing,  237 
welding,  227 
slip,  147,  148 

Buildings  in  shipyards,  159 
Bulb  angles,  65 
Bulkhead  liners,  112 

plating,  fabrication,  187 
stiffeners,  44,  122 
fabrication,  192 
Bulkheads,  44,  121 

water-tight,  124 
Bulwarks,  39,  128 
Buoyancy,  3,  233,  237 
calculation  of,  137 
centre  of,  4 
curve  of,  26 
Bureau  Veritas,  63 
Butt-strap,  173 
Buttock  lines,  32 
Button-head  rivet,  67 

points,  68 
Butts,  107 

calking,  220 


Calculations  in  ship  design,  methods, 
136,  146 

of  strength,  25 
Calibration  of  bunkers,  240 
Calkers,  176,  177 
Calking,  219 

testing,  223 
Camber,  37 
Cant  frames,  90 
Canvas,  used  in  ships,  72,  120 
Cargo  booms,  48,  49 

hatches,  45 

vessels,  58 
Carlings,  114 
Carrying  capacity,  62 
Castings,  steel,  64 
Cellular  double  bottom,  86 
Cements,  72-74 
Centre  keelson,  78 

lines,  2 

of  buoyancy,  4 

shafts,  101 

vertical  keel,  78 
Chain  cables,  47 

locker,  47 

pipes,  47,  127 
Chamfering,  110 
Channels,  steel,  65 
Chart  house,  48 
Chippers,  176 
Chipping,  219 
Chocks,  127 

Classification  societies,  62 
Cleats,  127 
Clinker  strakes,  112 

system  of  plating,  107 
Clips,  83,  173 
Coal  bunkers,  46 
Coamings,  45,  114 
Coefficients  of  form,  39 
Cofferdams,  129 
Collision  bulkhead,  45 
Comparison,  Froude's  law  of,  19 
Composite  ships,  51 
Concrete  ships,  52,  53 
Coned  neck  rivet,  68 
Construction  of  ships,  preliminary 
steps,  180-194 


INDEX 


245 


Construction  of  ships,  transverse  and 
longitudinal  framing,  78 

See  also  .Building  ships. 
Copper  in  ship  construction,  70 
Coppersmiths,  177 
Cork,  72 

Correction  to  displacement,  142 
Corresponding  speeds  of  ships,  18 
Corrosion,  protection  against,  224 
Cotton,  72 
Counter,  39,  98,  99 
Countersinking  rivet  holes,  166 
Countersunk  head  rivet,  67 

points,  68 

Cranes  in  shipyards,  158 
Crew's  quarters,  48 
Cribbing  of  ways,  235 
Cross  curves  of  stability,  140 

sections,  32 
Crown,  37 
Cruiser  sterns,  94 
Cruisers,  55 
Curve  of  bending  moment,  27 

of  buoyancy,  26 

of  dynamical  stability,  140 

of  load,  27 

of  shearing  force,  27 

of  statical  stability,  140 

of  weight,  26 


Dead  flat,  31 

rise,  37 

weight,  carrying  capacity,  62 

wood,  39 

Deck  beams,  23,  114 
fabrication,  192 

girders,  119 
Deck  plating,  114,  115 

fabrication,  187 

wood  over,  117 
Decks,  44,  114 

water  tight,  120 
Deep  frames,  82 
Definitions  of  terms,  2 

terms  referring  to  form,  34,  37 
Denny's  formula  for  wetted  surface, 

143 
Depth,  molded,  36-  - 


Depth  of  ship,  defined,  2 
Derrick  posts,  48 
Design  of  ships,  130-146 
Designers  in  shipyards,  170 
Designing  the  ways,  232 
Destroyers,  56 
Diagonals,  32 
Dimensions,  molded,  36 

of  ships,  defined,  1 
Directions  on  a  ship,  34 
Dished  plates,  107 
Displacement,  16,  61 

calculation  of,  137 

correction  to,  142 
Dock  trials,  240 
Docking  keel,  128 
Dolly-bar,  211 
Double  bottom,  47,  85 
Draft  of  a  ship,  2,  36 
Draftsmen  in  shipyards,  170 
Drag,  36 

Drainage  wells,  90,  129 
Drift  pin,  175 
Drillers,  175 
Drilling  machine,  pneumatic,  207 

rivet  holes,  166 

ship  frames,  207 
Drop-forgers,  177 

strakes,  111 
Dry-docking,  52 
Dutchmen,  222 


E 


Edge  calking,  220 
Edges  of  plating,  107 
Electric  welding,  229 
Electricians,  178 
Electrodes.  229 
Enamel,  74 
Endurance  of  ships,  28 

testing,  240 
Engine  foundations,  125 

room,  46 
Entrance,  37 
Equilibrium  defined,  7 
Erection  of  ship  frames,  195 
Erectors,  175 
Expansion  trunks,  49 
Extreme  drafti  36 


246 


INDEX 


Fabricating     and     erecting    shops, 

162 

Fairing  the  lines,  34 
Faying  surface,  68,  165,  187 
Fenders,  128 
Fitters-up,  173 
Fitting  out  a  ship,  237 
Flanges,  238 

transverse  and  longitudinal,  in 

a  frame,  79 

Flanging  plates,  166,  187 
Flare,  37 

Flat  plate  keel,  78 
Flitches,  71 

Floating  bodies,  law  of,  4,  5 
Floor  plates,  81 

fabrication,  191 
Floors,  bracket,  89 

solid,  89 

Flush  system  plating,  108 
Fore,  34 
Fore-body,  35 
Fore  foot,  39 

poppets,  233-235 
Forgers,  177 
Forging  steel,  167 
Forgings,  steel,  63 
Form  of  ships,  31 

coefficients  of,  39 

definition  of  terms,  37 
Formula,  Atwood's,  139 
Formulae  for  calculations  of  weight, 
etc.,  136-146 

for  wetted  surface,  143 
Forward,  34 

peak  tank,  45 

perpendicular,  36 
Fouling,  means  of  preventing,  72 
Foundations,  engine,  125 
Frame  benders,  171 

bending  and  beveling,  168 

spacing,  78 
Frames,  bossed,  101 

erecting,  195 

fabrication,  188 

spectacle,  103 
Framing  of  ships,  23,  41,  42,  77 

Isherwood  system,  58,  90 

longitudinal  system,  90 


Framing  of  ships,  transverse  system, 

77,90 

Freeboard,  2,  37 
Froude,  William,  18 
Froude's  law  of  comparison,  19 
Full  load  displacement  tonnage,  62 
Furnaced  plates,  106,  168,  187 
Furnacemen,  171 
Furnaces  in  shipyards,  162 
Fusion,  229 


G 


Galley,  48 

Galvanic  action  on  steel,  224 
Galvanizers,  177 
Galvanizing,  226 
Garboard  strake,  107 
Gasket,  120 
Girder  strength,  24 
Girders,  23 

deck,  120 

Girthing  frames,  181 
Greasing  ways,  235 
Gross  tonnage,  61 
Gudgeons,  21,  94,  97 
Gunboats,  56 


Half-breadth  plan,  32 

Half-breadths,  31 

Hammered  points  of  rivets,  68 

Hand  riveting,  216 

Harpins,  203 

Hawse  pipes,  47,  127 

Heart  of  timber,  71 

Heaters,  175,  176 

Height,  metacentric,  7,  8,  137,  240 

Heights,  31 

Helm,  20 

Hogging,  25 

Holders-on,  175,  176 

Holding-on,  211 

Holds,  45 

Hull,  22,  42 

machinists,  177 

material,  fabrication  of,  185 
Hydraulic  riveting,  168,  216 


INDEX 


247 


I-beam,  66 
Inboard,  34 

profile  plan,  135 
Inclining  experiment,  238 
Initial  stability,  7 
Inner  bottom,  47,  106 

plating,  113 

fabrication,  187 
Intercostal  plates,  84 
Interior  arrangement  of  ships,  42 
Iron  for  ship  construction,  69 

ships,  51 
Isherwood  system  of  framing,  58,  90 


Joggling,  109,  167 
Joiner  shop,  163 
Joiners,  177 

K 

Keel  line,  35 

plates,  fabrication,  191 
Keels,  23,  42,  77 

bilge,  128,  129 

docking,  128 

laying,  195 
Keelsons,  23,  83 
Kirk's  analysis,  143 
Knees,  71 

beam,  114 
Knuckle,  39 


Laborers,  175 
Landing  edges,  107,  135 
Lap-joint,  174 
Launching  ships,  231 
broadside,  157 
greasing  ways,  235     . 
plotting  curves  for  positions 

of  ship,  234 
wedging  up,  235,  236 
forces  acting  on  ship  during,  233 
Launching  ways,  147,  152 
designing,  232 


Law  of  comparison,  Froude's,  18 

of  floating  bodies,  4,  5 
Layers-out,  171 
Laying  of  the  keel,  195 

-out  shed,  162 
Layout  of  shipyard,  157 
Lead  for  ship  construction,  71 
Length  between  perpendiculars,  36 

over  all,  36 

Lightening  holes,  83,  173 
Limber  holes,  83,  90 
Liners,  bulkhead,  112 

in  a  frame,  83 

in  shell  plating,  107,  174 

passenger,  57 
Lines,  fairing,  34 

of  ships,  31,  32 

reference,  35 
Linoleum,  72 

on  decks,  116,  120 
Liverpool  rivet  point,  68 
Lloyd's  Register,  62,  229 
Load,  curve  of,  27 

draft,  36 

water  line,  32,  35 
coefficient,  40 
Local  strength,  27 
Loft,  mold,  161 
Loftsmen,  171 
Longitudinal  bulkheads,  45,  122 

metacentric  height,  240 

prismatic  coefficient,  40 

strength,  24,  25 

system  of  framing,  77,  90 
Longitudinals,  23,  86 

fabrication,  192 
Lugs,  83 

M 

Machine  riveting,  207,  216 
tools  in  shipyards,  163 

Machinists,  hull,  177 

Main  deck,  44 

Management  of  a  shipyard,  178 

Manganese  bronze  in  ship  construc- 
tion, 70 

Manholes,  punching,  167 

Margin  planks,  117 
plate,  87,  113 

Masons,  178 


248 


INDEX 


Masts,  48 

Materials  for  ship  construction,  C!> 
weights,  76 

ordering,  180 
Mean  draft,  36 
Melters,  178 
Merchant  ships,  57 

rudders,  98 
Metacentre,  7 
Metacentric  height,  7,  8 

calculations,  137 

longitudinal,  240 
Method  of  comparison,  to  determine 

power  required,  14 
Midship  section,  31,  36 

coefficient,  40 

plan,  134 
Mild  steel,  69 
Mining  vessels,  56 
Modified  girths,  143 
Mold  loft,  161 

offsets,  182 

Molded  dimensions,  36 
Molders,  178 
Molds,  making,  182 
Moment  to  change  trim,  141 
Moon  bars,  168,  190 


N 


Naval    architecture,    bibliography, 

145 

brass,  in  ship  construction,  70 
Net  tonnage,  61 
Neutral  equilibrium,  7 


Oakum,  72 

Offsets,  182 

Oil  stops,  205,  222 

Oil-tight  riveting,  217 

Ordering  material  for  ships,  180 

Outboard,  34 

profile  plan,  135 
Oxter  plates,  107 
Oxy-acetylene  blow  pipe,  167 

welding,  228 
Oxy-hydrogen  welding,  228 


Painters,  178 

Paints,  anti-corrosive,  226 
for  smoke  stacks,  75 
for  steel  strips,  72 
Pan-head  rivets,  67 
Panting,  27 

stringers,  27,  90 
Passenger  vessels,  57 
Passers,  175 
Passing  strakes,  111 
Pattern  makers,  178 
Peak  tanks,  45 
Personnel  of  a  shipyard,  169 
Phosphor  bronze,  in  ship  construc- 
tion, 70 

Pickling  plates,  187 
Piling  in  shipyards,  148 
Pillars,  between  decks,  118 
Pintles,  21,  94,  96 
Pipe  fitters,  177 
Pipe  stanchion,  118 
Pipes,  chain,  127 

hawse,  47,  127 
Pitting  of  steel,  224 
Pivoting  of  ship  in  launching,  155, 

234 
Plate  and  angle  shop,  162 

bending,  163 

margin,  113 

planer,  165 

racks  in  shipyards,  161 

rider,  113 
Plates,  fabrication  of,  186-192 

floor,  81,  191 

furnaced,  168 

intercostal,  84 

ram,  90 

steel,  64 

Planes,  reference,  35 
Planing  plates,  165 
Planking,  deck,  114,  115 
Plans,  for  ship  design,  32,  134 
Plating,  deck,  114,  115 

fabrication,  186 

of  bulkheads,  122 

shell,  42,  106 
Plumbers,  177 
Pneumatic  drilling  machine,,  2Q7 


INDEX 


249 


Port  side,  20,  35 

Portland  cement  used  in  steel  ships, 

75,  226 
Power    required   for    propulsion    of 

ship,  14 

Prismatic  coefficient,  40 
Profile  plan,  32,  135 
Propeller  post,  39,  94 

screw,  14 

struts,  100 
Propulsion  of  ships,  11 

means  of,  13 

testing,  240 
Protected  cruisers,  55 
Punching  and  shearing  shop,  162 

holes,  165,  186 

manholes,  167 
Putty  gun,  red  lead,  222 


Q 


Quarter,  39 

Quasi-arc  process  of  welding,  229 

Rabbetting,  92 

R 

Radio  room,  48 

Rail,  39,  128 

Ram  plates,  27,  90 

Range  of  stability,  9 

Rating  of  ships,  63 

Ratio  of  beam  to  draft,  40,  41 

of  length  to  beam,  40,  41 
Reamers,  175 
Reaming  rivet  holes,  166 

ship  frames,  205 
Red  lead  putty  gun,  222 
Reference  lines,  and  planes,  35 
Register  of  shipping,  Lloyd's,  62,  229 
Reinforced  concrete  ships,  53 
Requirements  of  ships,  2-30 

buoyancy,  3 

endurance,  28 

propulsion,  11 

stability,  5 

steering,  20 

strength,  22 

testing  for,  237 

utility,  29 
Residual  resistance,  19 


Resistance  of  a  ship,  15 
Reverse  frames,  80 

fabrication,  188 
Ribbands,  202 
Rider  plate,  113 
Riggers,  175,  177 
Righting  arm,  7,  8 
Rise  of  bottom  or  floor,  37 
Rivet  holes,  punching,  165,  186 

size,  215 

Rivet-passers,  176 
Riveters,  175 
Riveting,  209 

hand,  216 

hydraulic,  168,  216 

machine,  206,  207 

special  instructions,  218 

speed,  214 
Rivets,  66 

diameters,  215 

tack,  217 

tap,  216 
Rolling  chocks,  129 

of  plates,  187 
Rolls,  plate  bending,  164 
Rope,  72 
Round  up,  37 
Rubber,  72 

Rudder  post,  21,  39,  94 
Rudders,  20,  95 

balanced,  21 
Run,  37 
Rusting  of  steel,  224 


S 

Saddles,  125 
Sagging,  25 
Sawing  steel,  166 
Scantlings,  66 
Scarph,  91 
Scouts,  56 
Screw  propellers,  14 

vessels,  100 
Scrieve  board,  183 
Seam  straps,  108 
Seams,  107 
Second  deck,  44 
Set  iron,  168 


250 


INDEX 


Shaft  bracket,  103 

tubes,  100 

tunnels,  46 

Shafts,  wing,  101,  102 
Shakes,  in  wood,  71 
Shapes,  steel,  64 
Shearing  force,  curve  of,  27 

plates,  etc.,  165 
Sheathed  ships,  52 
Sheer,  37 

plan,  32 

strake,  107 

Sheet  metal  workers,  177 
Sheets,  steel,  64 
Shell  expansion  plan,  134 
Shell  plating,  42,  106 

fabrication  of,  186 

inner  bottom,  113 

seam  systems,  107 

thickness  at  ends,  112 
Shellac  for  ships,  75 
Shelter  deck,  44 
Shift  of  butts,  111 
Shipfitters,  172 
Ships,  building,  195-241 

buoyancy,  3 

description,  general,  31 

design,  130-146 

dimensions  denned,  1 

endurance,  28 

interior  arrangement,  42 

law  of  floating  bodies,  4,  5 

plans,  32 

propulsion,  11 

requirements,  2 

resistance  of,  15 

similar,  denned,  18 

speed  of,  60 

stability,  5 

steering,  20 

strength,  22 

structural  members,  77 

tonnage  of,  61 

types  of,  50 
Shipsmiths,  177 
Shipwright  shop,  163 
Shipwrights,  50,  177 
Shipyards,  147-179 

building  slip,  147,  148 

buildings  necessary,  159 


Shipyards  equipment,  169 

launching  ways,  147,  152 

layout,  157 

machine  tools,  163 

management,  178 

on  Great  Lakes,  157 

personnel,  169 

piling,  148 

site,  147 

steel  fabricating  processes,  163 

transporting  materials,  158 

traveling  cranes,  158 
Shops,  in  shipyards,  162 
Sight  edges,  107 
Sides,  39 

Similar  ships  denned,  18 
Simpson's  rules,  144,  145,  234 
Single  plate  rudder,  96 
Slabs,  bending,  162 
Smith  shop,  162 
Smoke  stack  paints,  75 
Snugs,  96 
Soldering,  227 
Solid  floors,  89 
Solution,    to   cover   steel   in  ships, 

73 

Spardeck,  44 
Spectacle  frames,  103 
Speed  of  production  of  steel  ships, 
214 

of  ships,  60 

Speeds,  corresponding,  18 
Spot  welding,  227 
Squeezer,  168 
Stability,  5 

angle  of  maximum,  9 
of  vanishing,  9 

calculations,  138 

cross  curves  of,  140 

dynamical,  140 

inclining  experiment,  238 

initial,  7 

range  of,  9 

statical,  140 
Stable  equilibrium,  7 
Stanchions,  between  decks,  118 
Staples,  117 
Starboard,  20,  35 
Statical  stability,  140 
Stealers,  111 


INDEX 


251 


Steel  for  ships,  63 

processes  of  fabrication,  163 

protection     against     corrosion, 
224 

quality,  69 
Steel  frames,  23 
Steel  ships,  52 

anti-fouling  process,  72 

paints  for,  72 

speed  of  production,  214 
Steering,  20 

engine  room,  47 
Stem,  37,  42,  91 
Stern  defined,  12 

post,  or  frame,  37,  42,  91,  93 

tube,  100,  104 

Stiff eners,  bulkhead,  44,  122 
Stopwaters,  205,  222 
Storerooms,  48 
Strains  in  ships,  25 
Strakes,  106 

clinker,  112 

drop,  111 

passing,  111 
Stream  lines,  12 
Strength  of  ships,  22 

curves  for  calculations  of,  26 
girder,  24 

local,  27 

longitudinal,  24,  25 
Stringers,  23,  83,  84 

panting,  90 

Structural  members  of  ships,  77 
Struts,  103 

propeller,  100 

Stuffing  box,  rudder  head,  99 
Submarine  Boat  Corporation,  159 
Submarines,  56 
Sunken  and  raised  system  of  plating, 

107,  109 

Superdreadnoughts,  54 
Surface,  molded,  36 


Tankers,  58 

Tanks,  double  bottom,  47 
peak,  45 

Tap  rivets,  216 

Taylor's  formula  for  wetted  surface, 
143 

Templates,  161,  183,  193 

Testers,  176 

Testing  ships,  237 

Thermit  welding,  228 

Tiller,  20 

Tipping  of  ship  during  launching, 
155,  234 

Tonnage  of  ships,  61 

Tons  per  inch  immersion,  141 

Torpedo  craft,  56 

Tramp  steamers,  58 

Transportation  of  materials  in  ship- 
yards, 158 

Transverse     bulkheads,     44,     122, 

124 

metacentre,  7 
system  of  framing,  77,  90 

Trapezoidal  rule,  144,  145 

Traveling     cranes     in      shipyards, 
158 

Trim,  36 

Trimming  ship,  45 

Trunk,  46 

Tubes,  stern,  100 

Tugs,  59 

Tumble  home,  37 

Tween  decks,  44 

Types  of  ships,  50 


U 

Unstable  equilibrium,  7 
Upper  deck,  44 
Uptake,  46 
Utility,  29 


T-bar,  66 
T-bulb,  66 
Tack  rivets,  217 
welding,  230 
Tank  top,  47 


Varnishers,  178 

Varnishes,  anti-corrosive,  75,  226 

Ventilating  ducts,  49 

Vertical  prismatic  coefficient,  40 


252 


INDEX 


W 


Wane,  71 
Warships,  53,  54 

construction,  88 

rudders,  97 

stem,  91,  93 

stern  post,  94 
Water  line,  2 

lines,  32 

Water-tight  bulkheads,  124 
decks,  120 

-tightness,  testing,  238 
Ways,  launching,  147,  152 

designing,  232 

greasing,  235 
Weather  deck,  44 
Web  frames,  82 

Wedging  up  ship  on  ways,  235,  236 
Weight,    calculating   for   launching 
ship,  234 

calculation  in  ship  design,  136 

curve  of,  26 

groups,  in  ship  design,  133 

of  materials  for  ship  construc- 
tion, 76 
Welding  steel,  167,  227 


Welding,  arc,  229 

electric,  229 

oxy-acetylene    and    oxy-hydro- 
gen,  228 

tack,  230 

thermit,  228 
Welds,  forms  of,  229 
Wetted  surface,  area  of,  143 
Winches,  49 
Wing  propellers,  101 

shafts,  101,  102 
Wood  calkers,  177 

for  deck  plating,  117 

in  ship  construction,  71 
Wooden  ships,  50 
Workmen  in  a  shipyard,  169 
Wring-off  head  on  rivets,  216 


Yoke,  100 


Z-bars,  65 

Zinc  in  ship  construction,  70 
protectors,  225 


BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL.  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


AUG  24  1942 


DEC  23  1942 

JUM  15  1943 

A  nn     ^i  tsf-    *  r\  M  j\ 

WH     JS    I9'(h 

LD  21-100m-7,'40  (6936s) 

YC  66317 


:J93750 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


